I found what seems to be a frame counter at 901812a4 and 901812b4, though I didn't check if this is static across matches. Now I could just shove my code in any place that runs once a frame, but is there any easy ways to find what writes to that address (without downloading a 4.0 fastdebug version).
Edit: 901812a4 resets and counts up in menus, 901812b4 doesn't count in menus but doesn't reset until starting a match. There's also a frame counter that starts after the countdown at 901807a4 and doesn't count in menus, the other two start at the beginning of the countdown. All addresses seem static for now.
Double Edit: Forgot to mention that anything I find might be different for anyone else looking: I'm doing these tests on Brawl Infinite with subspace emissary removed.
Edit: 901812a4 resets and counts up in menus, 901812b4 doesn't count in menus but doesn't reset until starting a match. There's also a frame counter that starts after the countdown at 901807a4 and doesn't count in menus, the other two start at the beginning of the countdown. All addresses seem static for now.
Double Edit: Forgot to mention that anything I find might be different for anyone else looking: I'm doing these tests on Brawl Infinite with subspace emissary removed.