Classic Mode in Smash 4 was great. I like how it had a different concept depending on which version you played:
Smash 4 on Wii U had you in a chess game and gave you some surprise matches at random moments during gameplay.
Smash 4 on 3DS was more of a Choose Your Own Adventure book. I was never a big fan of those, but it was really cool in this case!
And of course, the roulette system was pretty good too, even if it’s RNG was Knuckles’ Chaotix levels of terrible (trust me, when I played Knuckles’ Chaotix yesterday, you wouldn’t know how many times I wanted to go to Marina Madness or Botanic Base and ended up going to Techno Tower instead. XD).