To whoever is saying Ridley "fits better as a boss": I love bosses, but you know what I like more? Playable characters! I would love to see a Bowser just as epic as the 3D World one, but I prefer him playable, I don't know how I would react if Bowser was ever playable in a main series game, for me, the best part about any crossover game in general is playing as characters you can't play elsewhere, specially Smash, and seeing as Zelda and possibly Ganondorf(as he was teased at the end of the video) are going to be playable in Hyrule Warriors, Ridley is the only character that wouldn't be playable elsewhere, only in Smash.
Btw, I just got an argument with a guy about K. Rool and Bowser's size, I then asked f Kraid would work and he said 'yes', I then asked why and he mentioned Mini-Kraid from Super Metroid, basically what he said is: it works because it has already been done before(where is the punch trough internet button when you need it?)