I haven't done a Venusaur yet, so I can't speak specifically to it, but I've seen mixed results with Snorlax and Blastoise. My wife and I took a Snorlax to below 50% with 2 of us but barely got to the same spot with 3. The difference I saw between the attacks was how lucky or unlucky we got with dodges, more specifically how unlucky we were where the lag caused the Pokémon to take damage then have the HP returned. The critical loss of time, plus damage taken made a world of difference in the need result.
The other thing you don't know is how much time the other guys spent dodging, and what moves they had. If they had fire types with flying, electric or dark moves it wouldnf have done as much damage as fire moves, I'll also mention I see a vast difference between my 2700-2800 CP Pokémon vs 2000-2100 Pokémon on terms durability and damage.
I don't know how Niantic can deal with lag any better, I would just say they should error for the players, and worst case you get extra damage that the customer isn't upset about rather than what we have currently.