better bot than `SimpleHeuristicsPlayer` (e.g. RL-based)

[phinate]

we could greatly benefit from a bot that's really smart, since it could use teams in novel ways to win, helping us discover them!

[AoifeHughes]

https://github.com/AoifeHughes/poke-env/blob/e2f40982554440c79f46830dec256970db5c26e1/examples/openai_example.py for ref