Wario Land 4 is a weird one, since I think it could probably be counted as both the easiest and hardest game depending on what difficulty level you play it at.
Including Wario World and Wario: Master of Disguise?
Personally I'd say Wario Land 4 is probably the easiest one (at least on normal mode), while Wario Land 3 would be probably on the more difficult end.
But what do you think?
I don't think I can pick one to be honest. Breath of the Wild or Tears of the Kingdom would be up there, as would Wario Land 4... but so would Mario Odyssey, DK Bananza and numerous others.
Lol the idea of using Rudy as a Giant Baby Bowser replacement is great.
Would probably look better if his feet weren't visible though, since it'd make him look a lot bigger and more akin to the Yoshi's Island version.