In all the talk of graphical downgrades no one seems much preoccupied with 'why?'. Why build something and then proceed to tear it down, piece by piece, in the hope that ever more diminished expectations about the final product won't be severe enough to...
Learn what the power-ups in multiplayer do and make sure you use them to your advantage.
When you're underwater, you can jump much, much higher.
Don't try and get all the hearts, for it's not worth losing a life to get three more.