Played as the Warriors a bit in order to speed my process up the ladder in PNO, and the toughest game I played, the only game I had absolutely no shot at winning, was against an 00-01 Lakers user. I didn't have anyone inside who could stop Shaq, and Mark Madsen came off the bench and performed admirably when Shaq wasn't on the floor. Any team with a solid big has a shot at the Warriors. Spurs are a good choice too.
Also beat a Warriors user with the Blazers. 18 point lead when he quit before halftime. That was the only time I've played a Warriors user without a T1 team (thanks, matchmaking.)
Warriors are susceptible to bigs this year more than ever. Even last year I could abuse Draymond down low with Jahlil Okafor. This year I'll feast on the Warriors with my 6ers bigs.