Question

I just realized that his speed does not change upon evolution

Answer 1

Earthquake(coverage awesome with mold breaker)

Stone edge(STAB)

Fire punch(covers Ice and Grass)

Iron head(may flinch and has great power)

He is actually a good little cup sweeper becuase his speed is actually acceptable in it and he has the highest attack in little cup

Answer 2

Shock Wave

Earthquake

Zen Headbutt

Blizzard

Comments

Cranidos has horrible Special Attack, especially when compared to that amazing attack stat. Zen Headbutt isn't too good of a move due to poor type coverage and not being 100% accurate. It is only good if you use Sheer Force as an ability, but you made no mention there whether you are or not. Also, you have a lack of STAB.