
Having an assist trophy-esque item that spawns in a random NPC character (or maybe even existing characters with limited movesets/actions) and having it be moddable so that anyone can make an Assist character to add to the pool would provide even more longevity and appeal to Workshop.
Since assist characters have a much more limited pool of moves and animations compared to full-fledged fighters, they would serve as a great starting point for players who want to learn RoA2 modding, and they would take less time to make than a fighter. Having assists could incentivize more people to submit items to the game and possibly even move on to making full characters, too.