That moveset is good on defence and it's fine on attacking if you're dodging too.
Against a defender with Water Gun you're going to be using 1 Razor Leaf or 2 Vine Whips and they're more or less the same.
1 Razor Leaf - 15 damage, 12 energy.
2 Vine Whips - 7x2 damage, 7x2 energy.
Note that 15 and 14 damage might not actually make a difference to HP lost due to the damage formula rounding always rounding down.
The difference in energy is also unlikely to difference between having Petal Blizzard ready with Vine Whip and not having it with Razor Leaf, unless you're purposely not dodging in order to take more damage to increase your energy gain.
Assuming the opponent is also using a 50 energy move e.g. Vaporeon with Aqua Tail, then 3 cycles of Vine Whip in between dodges gives 42 energy compared to Razor Leaf's 36, so you still need to lose 16 HP to gain enough energy to use Petal Blizzard (2 HP lost = 1 energy) which would only happen by not dodging.
4 cycles would give 56 and 48 energy, and since you'll always take at least 1 damage per attack, even if the opponent's move does no damage (e.g. Splash), you'll still lose 4 HP and gain 2 energy therefore having 50 energy for Petal Blizzard with Razor Leaf.
