As far as I'm concerned, Awakening is a well-balanced cast, barring a few well-known outliers. I could easily see fitting most of the cast from 5-7, but that'd be boring, so I've exaggerated a tad. I've additionally been nice and generally weighted characters more toward where they shine - the aftergame matters more for the kids (almost all of whom would be a bit meh for the normal lategame due to spending it in catch-up mode) and less for the adults (many of whom are a bit meh then!). So yeah, results in an inflated average, which is good, that means that most of the characters at least have some niche where they're authentically good.
Characters I haven't used seriously in my 3 playthroughs get a ?.
Chrom - 7/10. Most reliable front-line beater early, hits 3 weaknesses between Falchion & Rapiers, gets Aether hax & Javelins late. A bit nervous to send him against true hordes alone, though, as his Aether/dodging rate isn't always reliable.
Avatar - 9/10. It's pretty hard for the Avatar not to be the best - even if you hate Tactician, Robin can Second Seal to whatever your favorite class is and have the right stat build for it. And will support with everyone, including hard-to-please types, and will have a level advantage thanks to Veteran. Tactician/Grandmaster is fine anyway, and Ignis & Rally Spectrum hold up in the aftergame if you care, or can be replaced by whatever crazy build you want.
Lissa - 5/10. Staff users are all kinda interchangeable, you want at least 2 but their stats don't matter THAT much. Lissa's your only option early, gets the earliest start on gaining levels, and if she got RNG-screwed you just replace her with Mari or Libra anyway. Also, Chrom tends to be someone I'll sometimes leave not paired-up, and he & Lissa usually have a good support, so if I need an emergency pair-up for him it's nice that his (also unpaired) healer also supports.
Frederick - 7/10. Gets you out of any scrapes in the earlygame, and also makes a solid Pair Up (+4 Str / +4 Def for Sumia? Yes pls). Is the Messiah in Lunatic earlygame. You probably shouldn't be using him directly by C8 or so, but even then, he makes perfectly decent Pair-Up bait if you want to keep using him.
Sully - 6/10. Averagey McAverage the Cavalier. She works.
Virion - 4/10. Virion is authentically useful for the first 10 Chapters + associated Paralogues or so! The battles are small enough that Virion can set up, chip down some dudes, and let others move in to finish them off, or vice versa. By the time you hit end turn, you've either killed everything or built a little wall around your squishy backline and Virion is in range of 0-1 enemies. Then you move forward again and repeat killing off more enemies. Meanwhile, Virion OHKOs all the flyers. ...then you hit the backhalf of the game. Suddenly, Virion's suspect speed growth bites him: he now fears getting doubled & OHKO'd, and the map design makes it much harder to protect an aggro Virion, and he's certainly not going to handle hordes by himself. Oh, and few characters care about a +SKL pair-up. He's not totally useless, there's occasional Longbow hax and he can still perma-hide in a Pair-up and let his wife get to slaughter fliers for free, but meh.
Stahl - 3/10? Meh. Stahl's in an awkward spot. He doesn't have quite the raw defense to be a Kellam / Nowi-esque tank who doesn't care if he's doubled, yet he doesn't have the speed to ensure he never gets doubled. At least going Paladin would help fix his Resistance some. Seems like he'd be among the characters who most benefit if you funnel extra XP his way, at least - an extra 5 levels for +3 DEF / +2 SPD suddenly means he's far harder to kill (unlike dodgy characters whose extra 5 levels might leave them still doubling & killing everything on your turn, and still killable via bad luck on the enemy turn).
Vaike - 4/10. The Vaike is practically your only option for axes early, and the boatload of HP means he's among the best in the game at eating 1-2 powerful attacks. Hero promotion gets him some badly needed Skill & Sol to increase his survivability. Still, the speed problems, which restrict his feasible pair-up options to speedsters, means I can't in good conscience give him too high a score, though he's absolutely usable. Is kinda trashy toward the end & in the postgame anyway.
Miriel - 4/10. A glass cannon with a bit too much glass and not enough cannon for my tastes. Also, the Avatar can cover frying Knights & Wyvern Riders with magic early, and Miriel will be competing against Tharja & Henry come the midgame. Far from a lost cause of course, especially if you get a Celica's Gale early, and worst comes to worst she can spam Physic Staves from the rear lines in the last chapters as a Lissa variant.
Sumia - 8/10. Amazing. Fast, dodgy, a great pair-up, flying mobility, good times. She has some minor issues - she can get STR or DEF screwed if unlucky, her support options are a tad limited, and she fears ninja assassins with bows. But whatever. Also gets bonus points for being by far the best Gangrel slayer with high RES / SPD / dodge / WTA.
Lon'qu - 6/10. Serviceable swordmaster. Makes for great pair-up bait w/ slower & tankier females or Vaike. Resistance problems can lead to some heart-stopping enemy turns (3 enemy mages who 2HKO Lon'qu but only have a listed 40% chance of hitting - does fate hate you?). Notably worse on Lunatic where he should just be a speed boost for some other character.
Donnel - 3/10? Way too much effort babying him early. To add insult to injury, he's not even particularly good for the deeper aftergame for all the work he takes. If I want to grind up someone with a bad start, I'll wait for the kids.
Ricken - 2/10? Ew. Okay, more durable than Miriel, but loses the ability to kill shit, and now fears getting doubled. Also, if I want a Dark Knight type who hits both defenses, you can breed some pretty scary kids for this purpose who will smoke Ricken.
Maribelle - 3/10. I have consistently gotten a worse Maribelle than Lissa in 3 games, more so than the stat topic would indicate - maybe Mari's meh base's fault. Risks both deadly OHKOs & doubles with her HP/DEF/SPD, and her magic is bad enough that Physic / Rescue's range can be a bit shorter than I'd like in the midgame. Still, staff users can only be so bad. (Also if you must have combat Maribelle, there's Falcon Knight / Dark Flier for the comedy option, I suppose. Especially if you can grab a Shockstick.)
Panne - 6/10. Taguel is not particularly inspiring, starts okay but seems to fade fairly quickly, and no WTA/WTD is actually worse for someone based around dodging. She does make a very good Wyvern/Griffon Rider if you're willing to spend that early Second Seal on her, though, she ends up Cherche with more speed (and THREE WEAKNESSES if on a Wyvern). Fears mages no matter what path you take, though.
Gaius - 6/10. Lon'qu with a rockier start & thief utility. Sure.
Cordelia - 8/10. See Sumia, but occasionally won't double (weird!), but has better STR & MAG and thus can go Dark Flier safely not needing the Lancefaire. Also summons Severa (sigh) which from a strictly mechanical perspective is pretty good. Is one of the rare adults who is deep aftergame qualified thanks to being able to dip into Sorc for the Vengeance-powered Falcon Knight w/ Tomebreaker & Galeforce.
Gregor - 5/10. Gregor is run-of-the-miller guy. Average stats all around, but perfectly serviceable. Erring to 5 rather than 6 because if he has a potentially weak stat it's speed (bad choice), and there tends to be a lot of strong competition in the sword-users category in your average runthrough.
Nowi - 8/10. Yes, Nowi's 30/5 stats are comparable to Tiki's L20 stats. Yes, she risks being doubled, especially without a pair-up. Yes, it probably violates child abuse laws to send her onto a battlefield. Doesn't matter. She's a champion tank in a game that rewards one. FEA throws too many enemies at you at times, especially in the later half, to try and math out potential survival rates. Nowi + a halfway decent pair-up (either DEF, SPD, or both) can cheerfully go trot into an enemy horde, draw their fire, and come out alive. And unlike, say, Kellam/Stahl/Gregor, her weapon naturally has 1-2 range, and her Resistance is good, too. Finally, even if you don't want to use her seriously, Manakete is a great pair-up, so you can slot-fill with her easily to buff a character while waiting for new recruits.
Libra - 5/10. Uh, sure, if you got Lissa & Maribelle killed already or something he's ready to go. Usually think that a Lissa should be barely behind him (L15) by recruit and will be better long-term, though. And of course all staff users bow to Anna. His front-lines ability fades later in the game - especially on Lunatic, where he's getting doubled & murdered by everyone a mere 5 chapters later.
Tharja - 9/10. Tharja has terrible skill, meh resistance, and can be pretty tricky to recruit (especially on Lunatic). And it doesn't matter because WTF Nosferatu. What makes the Dark Mages even more amazing is how they hack the AI: the AI, in the absence of a OHKO, wants to inflict the maximum damage possible, but is blind to how Nosferatu works. So while they'll ignore, say, Manaketes given the opportunity, they'll cheerfully charge the Dark Mages rather than get real damage on the bruisers.
Anna - 7/10. The ultimate utility character. Heals, dodges, thiefs, hits both defenses via Levin Sword… great stuff.
Olivia - 3/10. Blargh, Dancer in a game where it's more about drawing the enemy out on their turn than striking with your own offense, post C11 certainly. And if you do use her in an aggro strategy, and somehow something nearby lives, you better hope she dodges despite her massive underlevelness & meh Dancer XP, at least on Classic. Sure, if you stall for dance dance revolution grinding / EXPonential growth her to Second Seal range, she makes a perfectly valid Peg Knight or Myrmidon, but she still loses points for that initial underlevelness.
Cherche - 6/10. Hits like a truck, tanks physicals, and eventually gets lance or swordbreaker hax evade for the late game. Nevertheless, her poor speed makes her choosy in supports, and she fears a lot of enemies (mages / archers / dragonslayers), more so than the Pegasus Knights. Still fine of course, just have to be careful with her.
Henry - 8/10. Nya-ha-ha-sferatu hax rides again. Trades Tharja's skill problem for a speed problem, and a rocky start (whee getting doubled by some enemies on your join map). But high skill has it uses; he's better than Tharja at killing stuff dead with Waste, for example!
Say'ri - 5/10. RNG-proof Lon'qu you don't need to grind up (and notably better than Lon'qu on Lunatic). Loses a point for her extremely needy supports, though - the Avatar or Tiki, both in-demand? Ack. Better than the postgame crew on that note, at least.
Tiki - 8/10. See Nowi, except better stats, fewer missions, and a more restrictive set of potential supports. Awesome, in other words.
Basilio - 5/10. Probably great if you're doing a no-grind run, especially a no-grind Classic Ironman run or the like. Holds up surprisingly well on Lunatic, too, and can use a Killer Bow from the start for those C24 & C25 flyers. Still, a bit underlevel (especially if you've grinded even a little) & restricted supports = meh.
Flavia - 5/10. See Basilio.
Lucina - 8/10. Is Chrom with better stats but a level disadvantage, at worst. +1 point for various haxy options inherited from mom & aftergame suitability, as Lucina is very easy to build into your most potent offensive tool to kill things dead with thanks to Rightful King + Aether + any other proc.
Owain - 5/10. Owain's fine. You can make use of his decent Magic & Resistance as a Trickster or Dark Knight or something, or you can just have Astra & Swordfaire in any beatdown class like Paladin and mock mages with hungering sword hands. EDIT: Sure I'll dock him a point for parent issues.
Inigo - 4/10. Inigo's weird. He's probably a slightly weaker Severa if you're using Dancer Olivia on Casual (and non-existent w/ Dancer Olivia on Classic). He obviously gets way better if you can give him Galeforce which you are likely getting anyway w/ battle Olivia, although he won't complain about Astra or Swordfaire, but waiting that long leaves perilously little normal game left (since unlike Cynthia/Severa, Olivia is both underleveled AND had to Second Seal on over to get to Dark Flier). Obviously seems like he'd be pretty good in the aftergame. EDIT: I still don't know what to make of Inigo. IF you grind Olivia up a ton for Galeforce and grab him with overleveled parents, he does rock the aftergame, but he's so insanely unlikely to get for the main game, except for maybe late Lunatic w/ grinding. Call it a 4? Clearly worse than Severa...
Brady - 2/10. Underleveled Cleric, woo, when the main thing you care about Clerics is their staff ranking & their magic, and the thing saving them is their high level off of the XP bonus. Worthless for the normal game, but I suppose if you grind 'em up there's usual broken kid possibilities. EDIT: Even after grinding him up some, he's still bad. Yeesh, WTF, Brady. Down to a 2 you go.
Kjelle - 7/10. Tank in a game that rewards tanking. Good pair-up as a Great Knight for a lot of characters who want some extra Str/Def and move, like Lucina or SM Owain.
Cynthia - 8/10. I might have gotten lucky, but Cynthia has always been awesome for me, sometimes even more so than the Sorcs, which is high praise. Chrom!Cynthia has Aether and can just murder everything physically, is easy to catch-up, and probably inherits Lancefaire. Henry!Cynthia on Lunatic inherited Tomebreaker, which was huge, and could be a dangerous magey Dark Flier who hits both defenses and doesn't fear Wind Mages.
Severa - 8/10. Crazy stats, probably inherits Galeforce, has Armsthrift to be a good legendary weapon wielder. Probably inherited something useful from dad, too. Pint-sized murder machine with an inferiority complex.
Gerome - 6/10. Okay, if Gerome has access to Hero (easy), he can eventually set up the triple Breaker defense, which is kinda cool. Still, slightly uninspiring growths & speed and mom's fear of archers / mages / weakness-hitters can create some exciting moments when using Gerome.
Morgan - 8/10. At absolute worst, can be a Rally Spectrum bot. Otherwise, the Avatar with fewer missions and slightly more restricted support opportunities and the other gender's skill options.
Yarne - 6/10. Seems like being a kid might give him the raw stats to make Taguel work. Or he can just Second Seal to something else appropriate before returning.
Laurent - 5/10. Second seal him to Sorcerer immediately, get Sorc, hurray. Except he'll get some useful inheritance skill from dad, unlike Miriel (and maybe free Tomefaire from mom). Even then, kind of uninspiring, which is weird for a Sorc, and he's probably terrible if he goes Dark Knight or Sage.
Noire - 3/10. Better than Virion in every way except Strength both times I've recruited her. Unfortunately, the Sniper's time has already passed, so she's still worse. There's rejuggling her to something totally different a la Brady, but eh.
Nah - 8/10. See Tiki, pretty much, except a wider set of skill choices thanks to dad.
Gangrel - ?/10. I have failed to recruit Gangrel twice. Oh well. EDIT: Make that three times.
Walhart - 5/10? His stats are good, so I've used a Conquest-only Walhart just to fill a slot on Rogues & Redeemers 3, which works, I guess. He magically forgets the Aegis/Pavise/Luna/Rightful King combo he had before, so you have to grind 'em back up if you care about using him for Apotheosis, which I wouldn't due to meh supports.
Emmeryn - 5/10. Healer with good postgame stats & A-staff ranking basically ready to go. (Why they decided Miss Peace could zap dudes with Thoron I'm not sure, but not thinking too hard about this one.)
Yen'fay - 5/10. Analogies: Say'ri is to Lon'qu as Yen'fay is to Say'ri. Yen'fay has better stats and is even more RNG-proof than Say'ri, yet somehow has even fewer support options as he's Avatar-only.
Aversa - 8/10. Shadowgift, hell yeah. The best of the postgame lot by a mile. Why yes I'll have a Dark Flier with Vengeance, Tomebreaker, Shadowgift, & Galeforce running around Nosferatu / Waste / Brave Lancing dudes as appropriate.
Priam - Byblos/10. His recruit map is the last stage of the vanilla postgame, so N/A there. I guess he's mostly ready to go for Apotheosis if you need a slot filled, but I mildly prefer DLC Ike for actually having Aether rather than the Sol/Luna combo.
SpotPass characters - Not my cup of tea/10. I'm sure it's cool for some people they can make a team entirely of mage girls they met off the Internet, but eh. The retrogame-specific characters are sort of interesting, but since they're all splayed out in level, you can't really do a Path of Radiance characters runthrough of Awakening or anything.
DLC characters - No supports? Bleh. I did use a few for some of the late aftergame missions with very high deploy counts (Rogues & Redeemers 3, Apotheosis). DLC Catria is kinda ridiculous - Dark Flier w/ Lancefaire, Tomefaire, Galeforce, Astra, great stats, and perfect class choice, so she can easily grab, say, Rally Spectrum as well. 7/10. DLC Ike has Aether & random other useful stuff. 6/10, there's not much left to use him on but that's solid.
tl;dr: Sorcerers, Dragons, Peg Knights, & Lucina goooood. Ricken bad.
