@Soul: Yes you can get him, first you gotta have the dungeon Buried Relic, and he is on
9F-14F, or Darknight Relic 1F-6F!
I have the strategy guide and it says:
BLUE ONLY | RED ONLY
Aipom | Feebas
Lapras | Mantine
Magikarp | Plusle
Minun | Porygon
Porygon2 | Roselia