Welcome to CAF, Cadaverini!
Just to be upfront, I know nothing about Pokemon besides the fact that they are some of the most annoying playable characters in Super Smash Bros.
I think calling Pokemon the “spawn of satan” is probably a bit extreme. Not being familiar with the game, I can’t comment on it directly, but can only speak generally while thinking of other types of popular media that get labeled this way that I am more familiar with (Harry Potter, Magic: The Gathering, etc.).
I think with any such game, we do need to be cautious about taking it too seriously. I think that it’s probably only a small, small minority that would take such games so seriously they would lead to harmful spiritual side-effects. But it’s never bad to be cautious.
That said, provided one can separate fantasy from reality, it seems to me that one could play such games if one desires.
I think the greater danger is in looking to such things to fill the void in all our hearts that only God can fill. That danger is present in anything (TV, movies, books, games, collectibles, works of art, pets, boyfriends/girlfriends, etc., etc.). People turn lots of things into “idols” and devote undue attention to them. That doesn’t mean the things themselves are inherently evil. It just means that the person in question needs to realize that no material thing can fill that void. Only God can.