I messed around the save's name input screen and found out that you can make the selection go "out of bounds". Now I took a look at it in the game's memory and it turns out that on NTSC-U and PAL you can make the memory value for the selection go nuts with the right inputs.
How-to:
Enter save screen, select any file, select the letter V, press left and down at the same time and if the selection disappeared, it's out of bounds. Do the button combination with the DPad, then press Start and then Triangle to exit the screen.
Here's some combinations I've figured out so far on NTSC-U: (R - Right, L- Left, U - Up, D - Down)
R, D, U, L, U, L, D, R, D, L, L, R, U, R, U, R, D, R, R, R, L, L, L, D, D, D, D - Player 3 replaced by invisible dummy Kong
R, D, U, L, U, L, D, R, D, L, L, R, U, R, R, R, U, R, U, U, L, L, L, R, R, R, 7xU - Super speed in Crate Crush
R, D, U, L, U, L, D, R, D, L, L, R, U, R, R, R, U, R, U, U, L, L, L, R, R, R, R - Only melee does damage in Crate Crush
On PAL, the possible combinations only crash or don't do much. On NTSC-J, even though the glitch is possible, the value is capped on 2 of the 3 fonts, and the last one just softlocks when you try anything.
Memory addresses:
0BF19C - NTSC-U
0C11D4 - NTSC-J
0C89BC - PAL Black Label
Memory value notes of mine (bit messy):
http://pastebin.com/FW0yvERt
Updating with codes here:
http://www.speedrun.com/crashbash/thread/aunak
