In a similar vein to the suggestion about allowing both male and female characters to be in the same recruitment pool, I'd like to see the characters from FE8's Creature Campaign (those being Caellach, Orson, Riev, Ismaire, Selena, Glen, Valter, Hayden, Fado, and Lyon) added to FE8's main recruitment pool. While it would be nice to eventually have the people in the story match whoever their Creature Campaign equivalents become, I'd personally much rather have them added to the recruitment pool first.

Also note that I haven't entered Creature Campaign in a randomized file nor have I examined the code, so I don't know if there's anything more complicated that would prevent this from occurring. I also don't know if the playable Orson from Chapter 5x uses the same data as the one from Creature Campaign.