When it comes time for the Toriko+DBZ+One Piece crossover, assuming you decide to do it, the best way to explain how the match made them equal in power would be by explaining that the Blue Planet (One Piece world) has gravity 600x greater than Earth and is larger twice the size of Jupiter. Maybe explain Toriko's presence via a portal that occasionally opens that leads from the Gourmet world and only the higher ups know about. (Also that it changes location every time it appears)