The idea that Pokemon is lacking in depth in comparison to SoC is laughable.
Pokemon is the deeper, more original and more impactful title; and it isn't even close.
Pokemon has spawned over a decades worth of competitive multiplayer in a manner that can only be matched by titles like Starcraft. Twenty minutes of competitive play will confirm to anybody that it is not a title exclusively aimed at exclusively and children.
Sure the single player campaign is indeed very child friendly; but I can't see why this is a bad thing? Children deserve video games just as much as we jaded twenty-somethings do, and when a game for children managed to captivate its target demographic as successfully as Pokemon did, whilst being as educational as Pokemon is, I am going to give it a whole world of credit. The mechanical depth behind the Pokemon games is superior to pretty much every other RPG created, there is a strong focus on mathematics, problem solving, strategy and tactics. A small child can play Pokemon, but it takes a mature adult with months of study to play Pokemon well. With the possibly exception of chess, I can't think of another title that manages to appeal across the age spectrum so well.
SoC took a preexisting genre and slipped an artistic framework over the top of it. Shadows is eight really, really good boss fights, but nothing particularly new or revolutionary. Pokemon in contrast carved out a completely new genre for itself, in an era when video games where becoming more and more homogeneous. Pokemon was stunningly original, completely unlike any RPG that had achieved popularity beforehand, and there is a reason it took the world by storm.
Shadows of the Collossus is a game worshiped by gamers who want to consider games as art, but the problem is that SoC only holds up as a work or art when compared exclusively to other video games, and even that, doesn't hold up terribly well. Judged as an entity unto itself the game is not particularly profound. Hell; when you compare it to titles such as Deus Ex Machina or Worlds Apart it's positively shallow in its concepts. The execution is fantastic, but so is that of Gears of War, and I'm not giving credit to that. I'll grant that SoC holds more artistic merit than Pokemon, but then Pokemon is not trying be art.
There's the key difference. Shadows of the Collossus is trying to be a work of art, and isn't particularly successful as one.
Pokemon is just trying to be a accessible and phenomenally deep RPG, and does it better than any game ever produced.
Pokemon is one of those rare games that defined a generation. When a franchise achieves immortality then it is proof that it is doing something right; and when a franchise achieves immortality whilst being as original, challenging and complex as Pokemon is, then it deserves to be held as one of the most impressive feats of production in gaming history.
Also; Pokemon had Charizard. You seriously going to fuck with Charizard?