I've adimttedly imagined myself as one of the other trainers from Pallet Town who left at the same time as Ash and Gary. I would have started with Charmander, since that's my favorite starter, and occasionally challenge Ash or Gary to battles. Destroying a certain group of horrendously-incompetent Team Rocket members when they make feeble attempts at stealing Pokemon would be fun, too.
I agree about the bug-types. Personally, watching bugs from a distance is nice, but I really don't like it when one lands on me or something. I guess it's a good thing I'd be starting with Charmander! (Reports of massive forest fires near Viridian City still under investigation) Though I wouldn't mind having a Scyther on my team at some point.
My team would eventually consist of Charizard, Jolteon, Dewgong, Nidoking, Gardevoir, and either Scyther or Zangoose. If I could find and capture them, I'd put Zapdos and Suicune on in place of Jolteon and Dewgong.