Vileplume Offensive Moveset

RL/SB (assuming you're attacking water mons). RL/PB isn't bad either.

RL/SoB and RL/PB are both okay, but the main problem is razor leaf and how slow it is compared with an attack like Vine Whip. That's why Vileplume isn't that great an attacker, you're much better off with an Exeggutor, Venusaur, Tangela, etc.

I evolved 3, 3 moonblast.

I personally prefer petal blizzard over solar beam, despite solar beam having a higher DPS and total damage output. The reason is that in a typical match, I will usually only be able to use solar beam once, and will typically end up finishing off the other mon before it is charged again. However, I can usually pull off 3 petal blizzards in a match.