Question

there weren't any moves like energy ball in gen 3 and the move Sludgebomb (usually a great move for Vileplume) is a physical attacking move, I've already thought of Petal Dance and Moonlight but I'm not sure what else.

(Petal Dance and Moonlight don't need to be included if you don't think they're necessary)

Answer 1

I like Vileplume a lot, and while it's not the best ingame, this is one set I've always ran for it and it works pretty well :D

Vileplume @ Leftovers
Trait: Chlorophyll
EVs: 4 HP / 252 Special Attack / 252 Speed
Nature: Modest
Sleep Powder
Sunny Day
Solarbeam
Moonlight / Hidden Power Fire

A great set for in game, and probably its best shot at sweeping in gen III competitive play as well. With Sleep Powder, you can get a guaranteed chance to set up Sunny Day. Now, your Speed is doubled, and you get to abuse a 180 base power ( after STAB ) Solarbeam, as well as a Sun boosted HP Fire which covers Grass and Steel types. If this is ingame, you can ignore the EVs / Hidden Power if you wish. Moonlight is then the better option for lots of lovely healing in sun, allowing you to repeat the process.

Comments

UPVOTE for this. <3 this moveset!

Answer 2

Vileplume (F) @ Leftovers
Trait: Chlorophyll
EVs: 252 SAtk / 4 SDef / 252 Spd
Timid Nature (+Spd, -Atk)
Giga Drain
Secret power
Toxic
Hidden Power [Rock]