Chrono Trigger:
Crono: 7/10. Due to being forced, he's typically ahead of the team on skills, and he's got good speed when the first bunch of characters you get (sans short section with Frog) are the slowest 3. Good all around, and Life is your best source of Ressurection for most of the game
Marle: 5/10. Honestly not that special as a healer; Robo and Frog get MT, and dual techs that are just as good, etc. Life 2 is REALLY late, so hype for that vaguely boggles me, and Haste is only really worthwhile on bosses, and even then I got mild milleage out of it. She has good dual techs at least.
Lucca: 6/10. A bit lack luster early on, though a good early dual tech with Crono helps her through there, and once she gets Fire, she's always a good cannon. Her unique equips help her deal with some of her flaws a bit.
Frog: 4/10. Speed aside, there's never a reason to use him over Robo. Heal < Heal Beam, and his damage caps at Leap Slash. Some decent Dual Techs, but they're just not that special beyond how early and powerful Triple Raid is relative to the time.
Robo: 8/10. Bad speed is about his only flaw; low magic defense is really a minor weakness for most of the game cause the difference isn't big enough, due to the way the system works, until late, when he gets stuff like Moon Armor to make up for it anyway. Best Healer, excellent ST offense, good unites...yeah, MVP if you ask me.
Ayla: 7/10. ST damage version of Lucca, who has unites that let her cover crowd control...and has much better speed. Add in a Steal ability that's both accurate *AND* reliably gets you awesome stuff? Yeah.
Magus: 5.5/10. Would be higher if he was gotten earlier; having access to all 3 elements is nice, Dark Bomb is cost effective, but takes time to learn, and he's got actual speed. Lack of unites, and joining late thus way behind on techs holds him back considerably though.
Fire Emblem Lords, Dancers and Other Unique Classes:
Roy: 4/10. He's fine for the first half of the game, when people aren't promoted...but then they promote and he's useless and a genuine liability, and despite his awesome weapon, he's too underleveled to make genuine use of it (though he can get a lot of levels from the final dungeon if you use Hamerene, cause its ranged at least.) Nice supports save him some.
Merlinus(6): DNR. Doesn't function like a normal unit.
Elphin: 7/10. FE Dancer type, etc.
Lalum: 7/10. See Elphin! I think evasion style works better than Defense style as a Dancer, and I want to credit her for being on the superior path...but realistically, neither should see combat use, and you use them for exactly the same thing (if only Lalum could turn Douglas into a Green Unit -_-)
Fa: 3/10. If she's built up, and still has charges left, she's good in the very last chapter! I got nothing...
Lyn: 8/10. Reliable evasion tank who doubles everything and Mani Katti is pretty bad ass. Never held back on a promotion either, which is nice.
*Nils: 9/10. Dancer-type with awesome evasion and sexy buffs, yes.
Eliwood: 5/10. While not bad in and of himself, the fact that all Eliwood Modes hold back his promotion, and how he's at the mercy of the RNG really holds him back. Rapier's alright, but nothing special.
Hector: 7/10. Nice reliable tank, though a bit shakey on speed and accuracy. Loses half a point cause Hector Mode holds his promotion back.
Merlinus(7): DNR. Similar reasons as his previous form.
Athos: 7/10. Athos is incredible in the one map you have him, but I can only give so much credit for one map.
Eirika: 7.5/10. Felt worse than Lyn overall; while Rapier is better against hitting weaknesses, its worse than Mani Katti against regular foes. Siegliende would get her credit if it weren't for that fact that most of the cast is wielding big awesome legendaries by then (let alone Bishops exist.)
Ephraim: 9/10. I shouldn't have to explain this; he's a total bad ass on stats alone...and then he gets a stupid good weapon on top of that.
Tethys: 7.5/10. Elphin/Lalum, gains half a point for being better at the "surviving" thing, IIRC.
Myrrh: 3/10. Fa who can be more flexible in usage due to more charges, but lacks the "Last level ass kicking" aspect.
Ike(9): 7/10. Eliwood+, for the most part. Stronger stats, better legendary which he gets earlier (...barely...), but most importantly, he promotes earlier REGARDLESS of what route you choose for Eliwood, which is really quite a huge boon for Ike's use. Add in the awesomeness of Earth affinity, that's enough for 2 extra points.
Mist(9): 7/10. Bets healer in the game, Sonic Sword and Rune Sword are both excellent on her (though sort of require Arm Scrolls, if not two, to use), and not as big a liability as Rhys due to quick Jill support and doesn't get doubled by Myrms as regularly.
Reyson(9): 9/10. Nils, replacing Buffs with "Occasional 4 panel restoration, regen to adjacent units if applicable, and potential Canto." I think its an even trade.
Elincia(9): 4/10. Flying Healer is really cool, but that's quite literally all she has going for her.
Micaiah: 6/10. Destroys Mounted and Armored units, Sacrifice lets her heal front liners early, then she gets Staves so she's always a decent Healer at worst, and the instant A Support with Sothe. Wishes she had better speed though.
Rafiel: 7.5/10. Healing 4 panels = cool. Being less mobile than the other Herons = bad.
Black Knight: DNR (7/10. MURDERS the maps he's on, but one map is specifically designed for him, another he appears at the tail end of, a 3rd you don't control him on, so that leaves one map...which is possibly hardest map in the game, though he does contend with Nailah.)
Elincia(10): 9/10. FE9 Elincia if she did not require playing Catch Up, and had her offense increased by an absurd amount. If nothing else, she's at least got a strong case for "Most Improved Character between games."
Leanne: 7.5/10. More mobile than Rafiel, but only 2 PCs at a time. Eh, evens out I guess.
Ike(10): 9/10. Good at EVERYTHING but Res, where he fails, but his high HP, and loads of Bonds lets him work around that. Earth affinity is still kick ass, Ragnell is gotten earlier so he can actually make use of it, and...yeah. He was good in FE9, but he's pretty absurd here.
Mist(10): 5/10. Passable healer for the Greil Mercs, and a better long term investment than Rhys. Makes a good Fortify user if you want Micaiah on offense or something. Otherwise, she's really nothing special here, especially due to Elincia's improvement and the lack of Magic Weapons for her.
Reyson(10): 9.5/10. Its FE9 Reyson, only with Innate Canto *AND* he transforms much faster, and in the final chapters, is permanently transformed in practice at the cost of his first turn. His Weak Human form is such a minor factor as a result.
Sanaki: 4/10. Good for taking out Wyverns in the Desert, and innate Flare is nice, but...that's about it. She's frail, low speed, can't heal like other Mages. To her credit, she takes up a pre-determined slot in the Endgame arc, so she doesn't compete with anyone at least.
Lehran: DNR (6/10. You can give him blessed Balberith or Rex Aura and he'll be better offensively than Pelleas/Micaiah/the Saints, and he's a damn good staff user. Unfortunately, he's a bitch to get, lasts for only one chapter, and all that still requires spending a turn trading him that, and making someone useless offensively on the final boss.)