ITT: Pokemon that used to be able to learn certain moves, but can't anymore
For instance, Lapras could be taught Solarbeam in Gen I, but couldn't from Gen II onward.
Not a move as such, but
>125 SpA Articuno in Gen 1
I was more a fan of Mind Reader + Fissure Poliwrath. Throw in a Substitute and some Leftovers, and watch it wreck shit up.