I went and FAQ'd the reinforcements for FE13 chapters 24 and 25 because I remembered from Normal that they had stuff that would be a pain in the ass if they could attack on the turn they spawned. Sure enough, C24 had six forts spread throughout the map that would spawn Paladins, Great Knights, and Wyvern Lords on a rout stage, ugh. The former are at least hindered by all the forest tiles, but the Wyverns would've been a total pain in the ass if I weren't expecting them.
Meanwhile, chapter 25 shocking turned out to have actually REMOVED some reinforcements, instead of the usual tactic of making them spawn a turn earlier and sometimes adding a few extra rounds near the end. On Normal, a set of Dark Fliers and Griffon Knights arrive on turn 2 on both lower corners, but these are gone on Hard and above. Holy crap, I think IntSys actually playtested their reinforcements for once. Oh sure, the Generals spawn on turns 4 and 6 instead of 5 and 7, but those aren't ambush killing anyone.
Edit: C25 complete. I'm sandbagging the last stage so I can look up some details on how the Avatar logbook works, so I'll just compile some quick thoughts on my team this time before I forget. Doubt the finale's going to change my thoughts on a PC, anyhow.
Chrom, 20/18 Great Lord: S-ranked with Sumia. Great start and solid endgame. Definately appreciates a speed boosting Pair Up to reliably double fast enemies on Hard Mode, but someone less overkill than Sumia but who can do more than chip damage on Dual Strikes would probably be better overall. I briefly considered reclassing him to Great Knight for Luna until I noticed it would cost him 4 speed, which is painful even with +9 from Pair Up.
Sumia, 20/16 Falcon Knight: Much less useful without Frederick's strength boosts, she struggled to reliably one-round anything not weak to Beastkiller save the squishiest of mages (not even lategame Sorcerors, which kinda mattered). The high skill helps with activating Dual Strikes though, so Chrom got a lot of kills for her, especially with a Javelin equipped.
Julius, 20 Tactician/15 Grandmaster/12 Dark Knight: S-ranked with Miriel. He was defense screwed early on which held him in check, especially with a partner who wasn't boosting either his defense or his speed. Eventually the sheer quantities of levels fixed that flaw, though on Hard he never felt invincible or completely dominant without any form of draining. 8 move as a Dark Knight was pretty cool for getting him to the frontlines; Valkyrie would've been even better, but male Avatars are kinda boned on class selection compared to females in exchange for more flexible Rallybot children options.
Miriel, 18/15 Sage: Her offense was fantastic early on, especially right after she got Concentrate and Julius got Solidarity for ~33% crit rates with Thunder tomes in the first third of the game. Bad level-ups later on ultimately relegated her to Dual Strikes, mopping up stragglers for exp, and the occasional uber-ranged Rescue, sadly. Lack of durability was an issue the entire game - she could barely take a single physical attack for pretty much the entire game, and her Res wasn't that great either.
Panne, 10 Taguel/~13 Wyvern Rider/15 Griffon Knight/1 Wyvern Lord: S-ranked with Gaius. Panne's growths as a Wyvern Rider: 105 HP/75 Str/65 Skl/70 Spd/40 Luck/50 Def/20 Res. That's just nuts on paper, even by FE13 standards. Only problem is the initial speed loss from dropping a Beaststone, which Pair Up can alleviate. I think going for Griffon Rider before Wyvern Lord might've been a mistake in hindsight, though Deliverer is always nice at least.
Gaius, 10 Thief/~14 Myrmidon/15 Swordmaster/1 Assassin: He was supposed to just be Panne's speed-boosting backup, but somehow he ended up with 38 strength/44 skill/36 speed and was a total killing machine, especially with +Strength from Panne. 8 move while she was a GK, too. What the hell? I need to check if those stats are normal for him. Maybe I fed him a bunch of Energy Drops early on that I'm forgetting, I know all the mid/lategame ones went to Chrom instead.
Tharja, L20/20/6 Sorceror: Blah blah blah Nosferatu blah blah blah high defense blah blah blah Tomebreaker blah blah blah free damage boosts from Vengeance. I had her tank 30-40% of the map at times, hence the highest non-Avatar level of anyone. Clearcut lategame MVP.
Gregor, L17/6 Hero: I basically scanned the Pair Up list for a class that would raise both Tharja's skill and speed and settled on Hero. Poor Gregor basically never saw any action after chapter 9 since his speed and defense were both so middling, but he provided the essential stat boosts to make Tharja broken.
"Marth", 20/19 Great Lord: Actually trumps Gaius with 39 Strength/40 Skill/42(+2) speed. Turned out a lot closer to the one from my first file than I expected, albeit with higher average team levels and thus stats. No S-ranks so I mostly used her with Tiki, though she could fight separately pretty well if need be.
Tiki, L30/8 Manakete: Pretty great with those Hard Mode stat boosts, range 1-2 on a Manakete is fantastic and Pair Up/Rally Spectrum existed to fix any speed issues. I tried to mostly stick with regular Dragonstones when supporting and only switch to Dragonstone+ if she took lead.
Libra, L12 and Anna, L13: I am lazy on training staffbots in this game and just stick to the prepromotes for higher defensive bases. Mostly relied on Physic and Rescue lategame since both are storebought.
Olivia, level irrelevant: I'm resigned to the fact that she's probably the worst Dancer in the series for a variety of reasons, unless you grind her stats via reclassing. Still, she can usually give my staffbots and rallybots free turns safely and sometimes got rescued out after dancing for someone important. Dropped from chapters 21, 24, and 25 for safety purposes, though in hindsight 25 was workable.
Morgan, L19/6 Dark Knight and Laurent, L15/6 Dark Knight: Waited to recruit both until I could pass on Rally Spectrum, plus they got Rally Magic for good measure. Then I fed them what experience I could on their easy Paralogues (with more success on Morgan, obviously) and promoted them to Dark Knight for 8 move Rallybots who could take a hit without dying, finish off weakened enemies, and snipe the odd flier with Arcwind. This worked out about as well as I could've hoped, the Rally Spectrum spam was great lategame and both their durability and offense mattered on occasion compared to a 10/1 Rallybot. They pretty well justified my decision to pair my Avatar with Miriel this run, whom I largely picked for flavor reasons initially ("At the very least Julius should have a Sage wife, even if there's no silverish haired ones available!").