>>48795548Ignoring both autists in this thread, when you get it it does extremely well against Erika, the Silph Rival, both Giovanni fights, and Sabrina. So the creators pushed it to just after you beat Sabrina (you can actually get it before the fight with a Rare Candy) to balance out midgame a bit more.
It's also worth noting they also decreased several early mon evo levels like Masquerain or a lot of the Unova late game mons like Mienfoo to make early game smoother, it goes both ways. Corviknight I think is the only one with a shifted forward evo level