I've been "speedrunning" OvO for about a year, although I recently discovered other people doing it as well. PotatoJuiceUltra (who did most of the finding) and I discovered many of the same glitches that are used in speedrunning, and found more effective and consistent ways of doing them then most people know.

Main Glitches:

-Vertical Wall Jumps: (called wall clip by me and potato) Be sliding on a wall, and then press the opposite direction key, and up at the SAME exact time. Even if you keep holding the opposite way you wont go too far. Then just spam up.

-One Frame Momentum Jump: (called superjump by me and potato) As you hit the ground from a smash, hit up, and then down a fraction of a second later. Then hold a direction key. Hitting up then down at the right speed takes practice, but I normally do it by sliding my middle finger from the up arrow to the down arrow.

Other Glitches:

-33 Skip: When you spawn, walk to the left or right onto one of the ledges. As the red door opens, fall through without hitting anything, then dive to the right, anytime before you hit the ground as long as you don't hit the wall. You should go through the floor, unless you are on certain computers like mine.

-36 Skip: This one is hard. Nobody has found a very consistent way, but messing around with the 2nd spike crusher thing can send you through the ground to the end. The edge of the crusher must hit you into the roof as it goes up. Example:

-Flag Floor Clip: Anytime you are below the flag, (10,12,19,24,26,etc.), you can clip through the floor and hit the flag by diving underneath it, and then ground pounding when you are below the flag. Your hitbox will change to be taller, and your head will go through the floor.

-31 Fast: Level 31 goes by in just a few seconds but uses 3 different glitches. First, you superjump onto the front wall, and wall clip up on top. Then slide under the tunnel where the flag is and jump, and you will clip through and into the flag area.