On the topic of fighting games, what we also really need is a LEGO fighting game in whatever style. Just imagine the customization options, for one thing.
Maybe a very fitting gimmick for items play would be that you can collect multiple items at once to combine them into bigger and stronger items, so the characters could end up swinging around comically random mishmashes of collected objects, although of course it’d probably reduce your mobility and frame data.
It could also theoretically be an insane crossover of characters from different media if they really wanted it to be one, if LEGO Dimensions was any indication.