Because Big Mush Mario's hitbox is weird, 1.5 blocks wide yet can slip through a 1 block gap, it tends to break the expected physics of the game.

• How to Wall Jump in SMB1

Either how to create a black hole or different things you can do with one (that don't fit into a specific category).

• How to create a Humongous Clown Car
• How to make a 3D World Black Hole
• How to make a Black Hole in 2D themes
• How to make an Insanely Small Block

Using a Black Hole, we can make broken tracks, which allow very fast travel and/or teleportation of Mario and other enemies.

• How to destroy an entire floor of blocks at once
• How to make Bowser Jr. teleport into a wall

Glitches that involve clipping Mario, enemies, or items through solid objects.

• Big Pirahna clips blocks creating a cool one-frame door exit
• Boom-Boom clips into a Blaster, creating an elevator for him
• Cape Mario spins through On-Off switches and other things
• Clip hidden blocks activated by a ground pound
• Clip through tiny gaps using Link's bomb and shield
• Clipping a Spring through a corner
• Clown Car clips a Note Block creating an awesome troll
• Snake block makes Monty Mole walk through a Cannon

There are many glitches that are specific to cooperative play due to how things break when a second controller is introduced.

• Co-op vine corner clipping

This would be glitching enemies in certain ways that make them behave abnormally.

• A big Rocky Wrench that has the sprite of a small one
• A Boom-Boom that moon-walks (runs backwards)
• Koopa shell randomly stops moving
• Thwomp comes back from the dead

This is tech that uses a Black Hole, but in a specific way that allows you to put containers inside of containers. Because there are a lot of things you can do with this Black Hole technique, it deserves its own category.

• How to make a Claw spawn Power-Ups

This is whenever you make an object (usually a Bullet-Bill Blaster) move at a super crazy speed, and in ways that it defies the physics of the game.

• Simple 3D World Hyper-Speed With a Spring and Twister
• SMB1 night ground Mush, Note Block, Cannon, Sideways Spring Hyper-Speed

Importing 2D items into 3DW and vice versa. This will also contain glitches that use these mechanics to make them happen.

• How to import 3D World items into a 2D theme
• How to import a 2D theme item into 3D World

Glitches that are one item specific.

• How a Note Block and a conveyor can make Pows disappear
• How to ENTER a Blocked Pipe
• How to Ground Pound a Pow through a slope
• Note blocks that give items downwards (when hit from below)
• Quickly hitting an On-Off Switch with a P-Switch

These would be glitches that happen when the level ends, moves automatically, etc. Basically glitches that use level events in some way to make them happen.

• Make enemies survive after the level's over

These would be things that glitch Mario himself in certain ways.

• How to freeze Mario's outstretched arms
• How to remove Mario's legs

Glitches that didn't seem to have a specific category.

• How to make a growing hidden block bridge

Glitches that involve a Power-Up of some sort and don't fit in another category.

• How to shoot more than one Super-Ball, a lot more