Further information :

As indicated in the manual, the game supports Game Boy Advance connection and emulation.

1- To do this, select the GBA (integrated) option in the second GameCube port.

2- Then configure your keys by clicking on configure.

3- In the game, go to the Arcade menu and select Mad Trax. If it's not there, you'll have to progress or surely finish the game.

4- Once in the mode, read the texts and press A to start. If your virtual GBA makes a noise and has a lighted Nintendo logo, the connection has been established and you can start playing, confirming in the 2 emulated consoles.

This wiki talks about the many mini-games exclusive to the GameCube version: https://raymanpc.com/wiki/en/Mad_Trax
4-player mini-games work in the same way as Mad Trax.