I think many professional players are in agreement that solo maining in Ultimate is going to be extremely difficult as the average skill level increases. And without an overcentralizing character like Smash 4's Cloud/Bayonetta options, I think they're right. I think it's okay to solo main at this point since the meta is so underdeveloped and focusing on one character and they're unique options against matchups is a good call if you want to place well.
Bowser's definitely well rounded enough to consider the prospect of being a serious main. Great speed stats, great kill power and damage, every attack has a purpose. We've seen him as pocket choices from great players in recent major tournaments. His Up B updates make him way less helpless offstage in a game where offstage edgeguards are much more viable. He benefits more from engine changes than any veteran character I can think of. The new attack armor isn't fantastic but certainly interesting for creating mixups. The Fire Breath update gives him a much better mid to long range option, taking away the pressure of always having to approach or space with his sword arms. And his frame 6 air grab on side B is insane. I can't imagine wanting to switch, personally.
