Electric would be unfair.
Dark would be nice, like a Poochyena or something.
unfair to the water types? Like how rock is unfair to the fire types?
I would have thought that normal would be a kinda obvious choice for the first gym, seeing as none of the starters has an advantage.
Mr. Person is right, in Red, Blue, and Yellow, you evolve Caterpie to Butterfree and use Confusion. Skipping Johto, in Hoenn, you can get a Lotad or Seedot very early on, both having an advantage. In Sinnoh...help me out on this one, I haven't played that part for a while now.