if you were a gym leader, what type would you specialize in, what would your gym concept be, and what pokemon would you use?

I'd choose poison. My concept would be a research facility, where chemists study gases and poisons.

typical pokemon:
>koffing
>gastly
>foongus
>ivysaur

leader mons:
>amoongus
>gengar
>qwilfish
>weezing