Hey everyone, it's the master of grasster here. First off, I want to fix up my error about Meganium and Ditto: the 2 energy only counts on Grass pkmn.
Anyway, here's some of my favourite cards for each type. Although note: I'm different. I don't like using the cards everybody uses like Scyther or Sneasel. Sure, I use them as backup, but not as a main in my decks.
 
Grass:
Grass had to go first, as it's the best type. ^_^
 
Fave Grass card: Neo2 Beedrill.
It's got the best one-energy attack in the game, free retreat and can kill a normal Haymaker in one turn! 70HP gone for one energy!
Combos: With Rocket's Training Gym, or Dark Muk, or Murkrow to keep them stuck in place while they're being poisoned.
 
2nd fave Grass card: Exeggutor
It was a close race between these two, but the bee won. Being able to have 7 energy packed onto Eggy, that means a possible 140 damage. Even more with Meganium.
Combos: Meganium and Venusaur. Hard to pull off, but well worth it. Trans all energy over to Eggy in mid-game... say... 10 energy, which makes 20 with Meganium. Possible 400 damage!
 
3rd fave Grass card: Dark Vileplume
Can work as an attacker, so you can play trainers. But I prefer it as just a stopper of trainers.
Combos: Poliwrath, Golduck Use these guys to deny energy from the opponent with their attacks.