There are no "antagonists" in a story, there are never multiple antagonists. Naruto or One Piece are not exceptions, both have a ver clear antagonist. In the case of Naruto the antagonist is hidden between pawns or character with other goals, while in One Piece there is a unique antagonist but there are small antagonist per arcs.

There are no plural antagonists, there is just one.

Now with this clear, if you want to make different "villains" fight between each other, search causes to provoke that. Example: fight of power inside the group.

And the same goes for fights with the protagonist or secondary characters, search causes, and see how the character should manage it.