Venusaur

R/So is currently better of those two movesets for both offense and defense.

But hold onto the V/P. If Niantic decides to shift Petal Blizzard back to a two-bar move then that will be a good offensive moveset again.

Go to Venusaur's page and see ratings, DPS and stuff.

Those attack with charge move Solar Beam...
Or look for VW + SB....

Vine whip / solar beam. Before gen 2 PB was good but now it's the worst charge move in the game. Sad

Out of those two I'll vote RL/SB

DPS "paper" wise, PB deals more DPS than Solar Beam however pound for pound damage, Solar Beam wins. Petal Blizzard used to be an awesome move but now it's more like Psychic. I'd opt for the RL/SLB one in your case or if you can find one, an Extrasensory/Solar Beam Exeggutor.

RL/SoB is the best for attacking but VW/PB is the best for prestiging because both of those moves have a much lower CD allowing you to dodge better and RL/PB would be his best defensive double grass set because like I said PB has a much lower CD making it hard to dodge.

Solar beam is super usefull against low hp defenders to kill them before they use their 1 bar moves.
But since there is noway to kill a vaporeon before using a charge move petal blizzard can also work. You dont really need to dodge every water gun since its only 5 damage move.