Cod games at least have a different story every time, a different PvE aspect (zombies, Spec. Ops, Survival, Outbreak, Dead Ops, etc.), and a few different elements in their multiplayer (the pick-10 system, the gunsmith, etc.)
As far as I can tell, Pokémon has had the same story for a long time. And the combat systems are pretty much the same aside from adding other Pokémon and moves