i got nowhere else to document this so here it is

jump boost: this glitch allows you to jump higher than normal. after ground-pounding into a death thigger (like the void or spikes), it will enable you to jump higher than normal if you turn the opposite way you're facing. this is persistent until you die again, meaning it is carried through levels. You can go into a bonus level and ground pound into the void and exit and you will have it for the next run.

fake sliding: ground-pounding into a death trigger will also give the user the chance to gain crazy horizontal speed when they jump after respawning. it has something to do with the game being tricked that the character is sliding, and the speed has something to do with the ragdoll movement after death but i still have to look into it.

fast ground pound: if you ground pound on the edge where the floor and the breakable block meet, you can ground-pound the block and stay up where you are, recovering from the ground-pound faster and letting you move earlier.

spike jump: you can set yourself up in such a way that you can stand and jump off of the edge of a row of spikes.

orb double jump: when jumping off a purple orb from the bottom, you can jump again to gain even more height. this is useful in a few cases but still food to know.

checkpoint warp: avoiding certain checkpoints lets you intentionally die and respawn in a favorable spot. i only found this useful for the red key in #3.

cactus jump: sometimes you can jump off of cacti. you have to be on the very right-side edge of the cactus and you have to be holding jump because you can't actually land on it for too long.