Swap Glitch

You can't open menu during star is activating normally. But if you move between two different worlds, you can open menu.
This allows you to teach character move from other character for example.

How to do? (It's old and bad, just read new way)
1 - Get either of http://i.imgur.com/2MFaP5g.png or http://i.imgur.com/tuvqgCY.png
(1.5 - Gain exp, which doesn't need to be done but you definitely want to)
2 - Fall to hole then use trampoline if you use former star. Use trampoline then fall to hole if you use latter.
3 - If you did step 1 and 2 correctly, you can open menu.

New way
1 - Jump and press X at the same time
2 - Switch characters
3 - Close menu
4 - Gain EXP

How does this work?
Normally Level up bonus is given as following
Mallow <- Mallow's attack/defense... boost and bonus (+special move)
Geno   <- Geno's attack/defense... boost and bonus (+special move)

For example, if you switch Mallow and Geno from "switch" menu
Mallow <- Geno's attack/defense... boost and bonus (+special move)
Geno   <- Mallow's attack/defense... boost and bonus (+special move)

If you want to give mallow Geno Blast, he has to be Level 14 or more with star and switch with Geno. Geno's level isn't concerned, you just need to adjust character's level whom you want to teach different move.

This glitch works on any versions. (English, VC, Emu etc...)