I would have to say;
Gym 1: Chikorita and Jigglypuff (the best pokemon ever invented!) XD
Gym 2-3: Chikorita, Jigglypuff, and Togepi (after 4th Togepi will know Shadowball)
Gym 4-5: Chikorita, Jigglypuff, Togepi, and Aipom (if available)
Gym 6-8: Chikorita, Jigglypuff, Togepi, Aipom and...