I guess it's not a crime to bump these topics. It's probably better than making a new thread for this.
I was playing around with key through platforms, and it's amazing here. It varies depending on stage tilt and where exactly on the uneven ground your opponent is standing (those engines being slightly elevated helps you out), but just look at this list of characters you can hit. The first group can be hit under all three platforms, the second group can't be hit under the middle platform, and the last group can't be hit at all. A lot of them are kinda tricky to get, but the fact that it's possible is pretty cool.
Side and center:
Peach, Bowser, Donkey Kong, Link, Zelda, Sheik, Ganondorf, Samus, Zero Suit Samus, Pit, R.O.B., King Dedede, Captain Falcon, Charizard, Marth, Ike, Snake
Side only:
Mario, Luigi, Diddy Kong, Yoshi, Wario, Toon Link, Ice Climbers, Fox, Falco, Wolf, Pikachu, Squirtle, Ivysaur, Lucario, Jigglypuff, Ness, Lucas, Mr. Game & Watch, Sonic
Neither:
Kirby, Meta Knight, Olimar
I think Lylat Cruise is better for Mr. Game & Watch than initially rated. I like it better than Battlefield now.