Sonic and Mario is the seventeenth Co-op event match in Super Smash Bros. Brawl. Player One takes on the role of Sonic while Player Two uses Mario. These two face off against other Marios and Sonics, three of each, on Sonic's Green Hill Zone stage. The enemies will appear in alternating order, starting with Sonic. Two appear on the stage at a time, so killing both will result in one of each on the stage.
- The name and description of this event match imply that this event alludes to Mario & Sonic Olympic Games, the first official Mario and Sonic crossover.
- This is the only one of the sixty two events where a player uses the same character (Mario)-Co-Op Event 1: Two Trouble Kings-that was Mario for P1. For P2 in Co-Op Event 17: Sonic and Mario, P2 uses Mario-Mario from Single and Co-Op Event 1: Two Trouble Kings.