20 pokemons

1 Machamp (good HP, strong attacks)
2 Machoke (to evolve into Machamp)
4 Machop (easy 20 damage, evolve into Machoke)
1 Dugtrio (earthquake rocks)
3 Diglett (to evolve into Dugtrio, free retreat cost)
1 Onix (high HP)
2 Tangela (does damage and poison or paralyze opponent)
1 Nidorino (strong attacks)
2 Nidoran (to evolve into Nidorino, for a quick 30 damage)
1 Metapod (good HP)
2 Caterpie (to evolve into Metapod)

10 Trainer cards

2 Bill (for getting more energy cards)
1 Imposter Professor Oak(to trade away opponent's good hand)
2 Revive (to get our pokemons back!)
2 Gust of Wind (in case opponent has really good pokemons)
2 Potion (in case a good pokemon almost gets knocked out)
1 Energy Retrieval (to get more energy, energy cards are always useful)

18 fighting energy, 12 leaf energy