Such a great game...
First I wanna touch on this game's approach on the action platformer genre. It centers itself completely around boss battles instead of levels which is what I'm used to in most of these games, I really liked that aspect, it made the bosses way more memorable for me.
As for the abilities cuphead and mugman have, the 9 weapons in the game are adapted to many different situations, the super attacks have their use, so yeah there is room for a lot of experimentation, unless we're talking about charms where I feel like some charms are just way better than others.
Now about the run n' gun levels, I feel like there isn't much to say about them, they are cool and some of them are a bit hard to P rank but that's about it, it's not peak gameplay.
Last thing to talk about, the boss fights, most of them are quite good and offer a solid challenge aside from maybe The root pack and Goopy, they are also so aesthetically pleasing with their 30s animation style, they really feel like characters coming out of that era.
So yeah cool game, I liked it...