The Canyon immediately follows the events of Glacial Peak. The group at the base of the peak, consisting of Lucas, the Pokémon Trainer, Marth, Ike and the Ice Climbers, is overrun by Shadow Bugs released from the Halberd flying above them. From a cliff above, Mario, Pit, Link, Yoshi, and Kirby see their predicament and jump downwards to attack the incoming members of the Subspace Army. The 2 groups are forced to be joined together after this, now becoming the Canyon team.
Note that the first time through, one can only use Mario, Pit, Link, Yoshi, and Kirby, and cannot use the other five characters, even though they are able to battle.
The entire stage consists of one ambush.
After The Canyon is completed, Mario & Marth's respective teams now become one. When the player goes to previous stages, the character selection screen at this point of Subspace Emissary will group them in teams, with Mario's being the first, in this order. This is how the format is after The Canyon is completed up until The Subspace Bomb Factory (Part II) is completed, where all of the heroes up at that point are united back at The Canyon.
Plus second group
List of enemies
When the five characters jump from the cliff and during the battle, Battlefield plays.