Corrosion literally works on only toxic.
this generation yes, but next one can change that.
maybe we will get more Corrosion users? one mega and maybe some new ones.
Poison Powder?
can you Imagine Baneful Bunker+ Corrosion?
( I want a water/poison hippo starter with that combo)
Plus we may get other type based moves that cause poison status like Twineedle (bug).
Imagine a ground(Tar Pit- power 70, hits only pokes using special attacks and blocks their move),
steel (Quick silver special priority signature move),
ice (some fluids are poison and can freeze),
ghost , electric, fire or rock type move that may poison the foe?