Ok as we all know Sonic Battle is a spin-off, & spin-offs aren't supposed to affect the main series, so do yall think Sonic Advance 3 is a spin-off or Sonic Battle's a part of the main series?

I disagree with Battle being a spin-off.

However, if Sonic Advance 3 were to be a spin-off, that would make the rest of the Advance games spin-offs (a sub-series will not consist of both spin-offs and main series games), which would then make every game with Cream in it a spin-off, following the logic that spin-offs don't effect the main series.

Cream was in Sonic Heroes though... which is part of the main series. So the Advance series would have to be canon... which means that Battle would also have to be canon.

Yep, that was more or less my point.