Choosing Fast Moves

Base power and energy charge mean nothing if you don't take into account the duration of the moves. You want to look at Damage per Turn and Energy gain per Turn, or per duration. The choice then depends on your available charge moves and how the different moveset combinations perform in the key matchups you expect to play. Many pokemon only have one viable fast move because there's so much difference in performance.

In your example, VW has 2,5 DPT and 4 EPT, while RL has 5,5 DPT and 2 EPT. For Venusaur and Meganium with FP, both are good options. For nearly any other grass mon I'd recommend RL because that DPT is insane.

It depends on your overall strategy. Maybe you have other Pokemon who already have low-cost charge attacks, so you just want to do damage with this fast attack and maybe get a charge attack in late. Or maybe it's vice versa.

Razor leaf was just buffed to high heaven. It's the single most damaging move in PVP currently.

I was always of the mindset to burn their sheild early and sweep thru with heavy hitters. Razor leaf has become so strong if you are resisting your opponents hits and dealing super effective damage you can easily tear thru one, two, and very close to the third mon if they made bad type choices.

My bellosom did a mean sweep to a kaiogre and groudon yesterday, managed to burn both shields and stick retained one of my own. Even fired off an additional leaf blade to the third mon before fainting.

If bellosom can do that, I'm certain a 'good' mon could have gotten thru the third.

While I still prefer moves like mud shot and fury cutter its hard to ignore razor leaf and confusion since the recent buff.

Try them both out for yourself