yuhhuh, here they r
For RED only...
Feebas/Milotic (duh, evos)
Mantine
Plusle
Porygon
Roselia
Blue exclusives
Aipom
Lapras
Magikarp
Minun
Porygon2(carzy ain't it...)
the good news is u can still recruit them, not thru trading, but thru wondermail. Go to the request thread for wondermails, and simply request a mission where the client is the pokemon u want in that game. Once u have completed the mission, said client pokemon will start appearing in the dungeon where they normally appear in the opposite game, hope that helps

I got this from the Prima game guide book for the PMD game, well, it rlly helped me out...