dainbramage
Smash Journeyman
AFAIK, this is what happens:
Frame -2: Jump input
Frame -1: Usmash input
Frame 0: Last frame of hitstun
Frame 1: First frame of jump animation. Game realises you can upsmash.
Frame 2: First frame of upsmash animation
..
Frame 9: Upsmash hitbox
Frame -2: Jump input
Frame -1: Usmash input
Frame 0: Last frame of hitstun
Frame 1: First frame of jump animation. Game realises you can upsmash.
Frame 2: First frame of upsmash animation
..
Frame 9: Upsmash hitbox