serebii.net , search for Empoleon's page and there are all of his learnable moves.
Gyarados cannot learn the move Hydro Cannon. Hydro Cannon is a move that can only be learned by the Water type Starter Pokemon.
Pokemon learn moves at there time. Empoleon learns Hydro Pump at level 59 because it can!! Because every time you evolve3 a Pokemon its stats get better but the learning of a new move takes longer. So, for example, if you had stopped the evolution of prinplup to empoleon you could have learned hydro pump at lvl 51.
zubat and its evolutions learn mean look at level 29-33
Mean Look isn't a TM or HM, therefore can only be obtained by levelling up a Pokemon with the capabilities to learn Mean Look, or by breeding a Pokemon to have Mean Look as an Egg Move.
Well the only way I got it was through my golbat at around lv 40 - 50
Empoleon learn's it around the 70
mist
Empoleon cannot learn the move Aqua Blade. This is primarily due to there being no move called Aqua Blade currently in Pokemon.
you have to have the move tutor teach it
Eventually if you level up your Pokemon then it will learn the move mean look. For example watchog will learn mean look
Empoleon is not able to learn the HM move Fly. Typically only Flying type Pokemon can learn the move Fly with only a small handful being the exception. And most of those exceptions have the ability Levitate.
speed wing a really powerful move
Empoleon doesn't learn waterfall unless you teach it with an HM.
The move Mean Look is not a TM nor is it available from a Move Tutor. The only way to get one to learn it is if they normally learn it by level-up.
Gastly should learn mean look at level 8 :)
Drill Peck at level 52
Golbat