- Unlocking a certain stage or extra
- Holding down a certain button combination
They can also be triggered randomly.
Alternate music for normal stages
Every time any one of these stages is loaded up in Vs. Mode or Training Mode, there is a 12% chance that the alternate music will play instead of the normal music. If L is held by all players while the stage is loading, the alternate music will play, however this only works if the alternate music was played in the past in the stage the player is trying to load. Battlefield and Final Destination stages have two separate songs from a Multi-Man Mode as their alternate music. The rest of the alternate songs are from other games.
The alternate music for normal stages are:
- Icicle Mountain: Balloon Fight
- Great Bay: Saria's Song
- Temple: Fire Emblem
- Yoshi's Island: Super Mario Bros. 3
- Pokémon Stadium: Battle Theme
- Big Blue: Mach Rider
- Onett: Mother 2
- Kingdom: Dr. Mario
- Kingdom II: Dr. Mario
- Battlefield: Multi-Man Melee 1
- Final Destination: Multi-Man Melee 2
Alternate music for Adventure Mode stages
On the screen that shows what stage is coming next in Adventure Mode, alternate music will play on some stages if the player holds down L, R, and presses START, while keeping L and R pressed until the music starts. An alternate theme will play for some of the stages. This only works for the first stage in each area: for example, on the F-Zero Grand Prix, only the first level will have the special music.