I really want a Mario Warriors game. The Warriors games are already easy to pick up and play and get into, so not much more simplification is needed, plus Mario is a massive franchise with so much characters to be used, ranging from the typical cast you see in Mario spinoffs to outright Mario RPG characters from either Mario & Luigi or Paper Mario, including allies or villains, and such characters from those games can bring so much to the table in terms of their personality and what kinds of movesets they are able to have. Warriors titles can always do a massively nonsensical storyline to boot with ridiculously high stakes completely disregarding any sort of real continuity between all Mario/RPG titles whatsoever (like in the Warriors Orochi and Hyrule Warriors), and having a massive ensemble gather together with whatever clashing themes and art styles simply because it's the fun thing to do.
A Warriors game is one of the only Mario spin-offs that I would geniunely would want to see RPG characters playable and referenced just because their potential to have a fun moveset and unique personalities mesh well with the hack and slash gameplay and what kinds of dialogue they can have when KOing enemy officers or reaching 1000 KOs and the like is endless, plus content from the RPGs can also offer unique peon armies and smaller scale officers that you can also face off against as well.