I am from Canada, but my entire team is from the USA.

Is there a strict rule that I am unable to represent USA?

Do I have to find a comepletely new team and represent Canada if i wish to participate in WCG?

i was wondering the same thing also. Im from Australia but i wouldn't mind representing America

there's a strict rule that you're allowed to represent teams from your own nationality.
that's the whole point of WCG. representing your country, not just your team.
the qualifier for each country usually check your passport to confirm your nationality.
so yes, you have to find a new Canadian team if you want to compete in the WCG.

Yes, Platoon. All players on a WCG team must be from the same country and participate in that country's national qualifier.

Most other events going forward will not have this restriction.