Yes, it's a tm.
Solarbeam as he mentioned, or Pursuit and Counter, or resttalk.
Fire punch over thunder, thunder wave over either iron tail or light screen.
Ditch either water move for rest. There's not much you can do with toise, and body slam is an idea, but meh. I prefer counter/mirror coat. In fact, I hate Blastoise....
Twave over Shadow Ball on a defensive set.
Curse/Flametrhower/Surf/Thunderbolt/Ice Beam/Rest/Roar over Toxic. Tar has an excellent movepool. You figure out what you like best.
Return over Double team I guess, curse over fly.
The GSC Militia: