Ran into a Curse Venusaur today, the only three moves used were Curse, Earthquake, and Synthesis. I think it's a pretty safe guess that the last move was Power Whip which he did not use, since I fought it with Goodra and he probably guessed I had Sap Sipper (I did). Goodra seemed an alright counter to it, even a +2 (or 3?) Earthquake only did about 1/3. The problem was I couldn't really do much back either, he could PP stall me out of Dragon Pulses. I only beat it because I got a crit with Flamethrower and got a burn. Although when you use a set like this, I guess you gotta be prepared for an eventual crit.
Not sure how great this set is, it seems really reliant on team match-up. Pretty much all Flying-types can beat it, since they are immune to Earthquake and resist Power Whip.