How do you get Sonic to join your party in Subspace Emissary?

You have to reach the Subspace level and after trying to fight Tabuu again, Sonic will come, smashing Tabuu's wings.

ok so heres how:u have to play the final level and complete the great maze then tabuu will appear with sonic

The Adventure mode in Super Smash Bros Brawl. It's where Brawl characters have to fight the Subspace army, who tries to capture different places into subspace and capture the characters' powers. Some...

It doesn't affect the story, but it gives you less people to choose from for the rest of the game. However, not getting Cream means you can't get the Chao Cheese.

No