Have you noticed the moves a Dunsparce can learn?
EARTHQUAKE, ROCK TOMB, FLAMETHROWER, FIRE BLAST, WATER PULSE, SHOCK WAVE, THUNDERBOLT, THUNDER, SOLARBEAM, ICE BEAM, BLIZZARD, STRENGTH, ROCK SMASH...

Isn't that asking a bit too much from the poor little thing? O_o

Oh, and Dewgong with Signal Beam too. Only non-bug pokemon to learn it. Reason: unknown.