/vp/ is not a "containment" board. It was needed because a franchise as big as Pokemon NEEDS its own board.
Pokemon covers a lot of media including /v/idya, chinese c/a/rtoons and comics, TCG and /toy/s. You'd see why /vp/ need its board especially when shitposters from other boards will spam
>>>/v/ when they're clearly talking about PokeSpe or
>>>/a/ when it's clearly about Mewtwo in Smash Bros Brawl