w00t Grass types = pwnz0r!!!
My favorites:
Sceptile
Victreebell
Shiftry
Sword dance Sceptile so pwnz cuz not many ppl can really predict that - (Adamant or Jolly) SD + EQ + BBreak + AAce (or RSlide). because Sceptile is fast and ppl tend to switch a Fire type or Bug type into him and they'll just get pwned by a EQ or AAce after 1 or 2 SD. This set also so screws up Blissey's :D Heracross get pwned by AAce, if u want to counter Charizards then go for RSlide instead. it worked for me so far in Netbattle.
EV's:
(Adamant) 168 attack, 252 speed, 88 def or HP.
(Jolly) 252 attack, 168 speed, 88 defense or HP.
This way u can par or outrun Adamant Dugtrios and other Sceptiles.
Item:
Lum Berry - for Jolteons, which always outruns it, that tend to TWave you first.
Give it a try if you want to play random :D