A regular PKM from 4th gen transfered to B/W using PokeTransfer and edited afterwards will work just fine. However, PKM created from scratch, although every stat and field seems valid, just won't show up in the pokedex. Is there a way around this?
Edit: Leaving the PID blank for the pokemon in PokeGEN seems to have fixed the problem, but I'm still unsure what the exact cause was. Is the PID generated by PokeSAV automatically invalid?