level 50
LT. Surge has a level 28 Raichu and that's it.
In Pokemon FireRed and LeafGreen, Diglett can learn Dig at level 17, which is a nice and early level for a good move.
just use high level pokemon that have ground type moves, since hes eletric =]
level 36.
all of them should be around level 50-60
Brock, in Pokemon Red and Green/Blue, has Onix (level 14) and Geodude (level 12) as his main Pokemon.
For LeafGreen and FireRed, Lt. Surge is going to carry the following Pokemon: Voltorb at level 21, Pikachu at level 18, Raichu at level 24. My best recommendation is go with the opposite type that he's using and go with a ground type Pokemon such as Marowak, Dugtrio, and Rhydon. In the case that you can't use a ground type Pokemon, the only thing I can recommend you is some good old fashioned training.
You can receive a Level 10 Squirtle in Pokémon Yellow after beating Lt. Surge in Vermillion City from Officer Jenny, a police officer near the Gym.
the answer is level 20
Level 934, that's the highest they go.
Krabby will evolve into Kingler at level 28.
Mewtwo is at level 70 when you find it on leaf green.