Recommended starting Pokemon
Squirtle's water attacks are not very effective on Misty's Pokemon. It will be destroyed while battling Electricity, Grass, and Poison types in the next three gyms. It would be average against Psychic types and does well against Fire types and will be fine in the last gym.
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Bulbasaur will do well against Rock and Water types. It will also do fine with Electricity types, but will not do great with its own type and Poison. It would do well against Psychic and bad against Fire types. It does well in the eighth gym..
Charmander will not do very well with Rock or Water types. However, it will do well with Electricity and destroy Grass and Poison types. It does well with Psychic and average with Fire. It does not do very well in the last gym.