In a 2v1 match, Electrode + Flareon can beat Mewtwo 85% of the time.
1. Electrode uses Screech
2. Mewtwo uses Amnesia/Psychic
3. Electrode uses Explosion
4. Flareon uses Quick Attack
I say 85% because Screech has an 85% success rate.
I'm guessing only a critical hit Hyper Beam at the start...