I am the biggest hater on Alomomola and it is incredibly annoying but I think it's checks and counters are prevalent and good Pokemon in the tier. When Greninja was banned it was because people were running things like Porygon-2 and the fat fish itself which were dead weight against most teams that didn't have a Greninja. People had to resort to using overly-niche Pokemon to counter that thing and that is what I think of as overcentralizing. I