Chrom-Great Lord
Robin-Varies, otherwise Grandmaster, Dread Fighter(M), Bride(F)
Fred- Wyvern Lord
Lissa-Valkyrie or Dark Flier
Sully-Great Knightress
Virion-Bow Knight
Stahl-Great Knight
Vaike-Warrior, Hero, or Zerker
Miriel-Sage, Sorceress, or Dark Knightress
Sumia-Dark Flier
Kellam-General, Sage, or Assasin
Donny-Warrior, Hero, or Bow Knight
Lon'qu-Assasin or Swordmaster
Ricken-Sage or Dark Knight
Maribelle-Valkyrie, Dark Knightress, Sage, or Dark Flier
Panne-Assasin or Wyvern Lady
Gaius-Assasin
Cordelia-Dark Flier
Gregor-Hero or Bow Knight
Nowi-Wyvern Lady
Libra-Sage
Tharja-Sorceress or Dark Knightress
Anna-Assasin
Olivia-Dancer
Cherche-Wyvern Lady
Henry-Sorceror or Dark Knight
Lucina-Great Lady
Say'ri-Swordmistress
Tiki-Varies
Basilio-Zerker or Hero
Flavia-Assasin or Heroine
Gangrel-Assasin
Walhart-Varies
Emmeryn-Dark Flier or Sage
Yen'fay-Swordmaster
Aversa-Dark Flier
Priam-(Radiant) Hero
Owain-Assasin or Swordmaster
Inigo-Hero or Bow Knight
Brady-Sage
Kjelle-General, Great Knightress, or Swordmistress
Cynthia-Dark Flier
Severa-Heroine
Gerome-Wyvern Lord
Morgan-Varies
Yarne-Swordmaster, Zerker, Paladin, or Warrior
Laurent-Sage, Sorceror, or Zerker
Noire-Sorceress, Dark Knightress, or Sniper
Nah-Wyvern Lady
So there's my chronologically-ordered opinion list of who should be what class by the end of the game,opinions are welcome.
This is before Grima
This is my opinion
This assumes the unit has been every other class they have access to