We see that in all the arcs, all the guardians were drawn into fighting at some point. So far the Game Choice has only used 3. And this arc has made it a point of involving the usually non-powered members of the KHR crew so I get the feeling they might have a bigger part to play.
So basically I see 3 ways that the rest, especially the 3 other guardians, would get the chance to be involved.

1. Byakuran actually cheats so they have to cleverly get involved.

2. They somehow tie in this "Chance" game necessitating a 2nd round.

3. Byakuran loses or wins and just follows on some plans after "Chance".

4. Some combination of the above events leads to them needing to be involved.