Keep/Change/Delete

[Frozen Fennec]

Keep as it is, seems decent enough.

Thunder Fang

 

[Giant Octopodes]

Like all fang moves, I'd bump the accuracy up to 100 base and knock the power down to 60 base.

Shell Smash

 

[Camille]

Keep it, it is a great boosting move.
Dragon Breath

 

[hanecco]

Change: make its base power 80 so that it's actually useful in higher-level battle (think vs. Elite Four or in competitive). Then again, it's usually learnt by lower level Dragon Pokemon, so it might be a little too overpowered with 80 base power and a 30% chance to paralyse.

Meteor Mash

 

[Camille]

Keep it, it is fine the way it is now.
Brine

 

[CynthiaLover]

Keep it. It's a good move overall and has an interesting effect that gives it some merit.

Muddy Water

 

[Camille]

Make it a 95 base power attack once again.
Sky Drop

 

[Couple's Consoling]

Sky Drop

Keep it. It's cute and flavorful and has a lot about it that makes sense - ie, flying types can't get damaged by it and you can't pick up heavy Mons. I like that.

Perish Song

 

[Camille]

Keep it, it is gimmicky but not useless.
Water Pulse

 

[Giant Octopodes]

Keep it, it is gimmicky but not useless.
Water Pulse

I'd change it to guaranteed heal the burn of the target (the same as Sparkling Aria) instead of having a chance to confuse. This is because a staple mid tier water move doesn't need to be a clone of Psybeam, and it both makes more sense to me and provides more strategic uses to have a burn heal available to a variety of water types instead of as a signature move. It also is more useful to have a burn heal on a more mid tier powered move, since it's less damaging if you intend to use it on your own Pokemon in a double battle.

Sludge

 

[CynthiaLover]

Keep it. There isn't much that needs to be said about it, so I see no harm in leaving it be.

Charge Beam

 

[Camille]

Maybe make its base power 60 and boost accuracy to 95%.
Headbutt

 

[Giant Octopodes]

Keep it, it's a solid move whose power and effect make sense, it also makes sense for it to do slightly lower damage than say Iron Head.

Splash

 

[DLEBLOBOL]

Keep.Its a troll move so we should keep it because the joke would get ruined. Though they are overdoing it with how many pokemon learn that move.

Rivalry (ability)

 

[Camille]

Delete, just too situational to be helpful.
Hidden Power

 

[Nicolas721]

Revive it (?), make its type fully visible, and don't give it to Unown. It can have a much better signature move with many letters attacking the opponent or something like that.

Life Dew.

 

[charlycicero]

Life Dew.

Keep, and give it to more Pokemon.

Skull Bash

 

[Camille]

Maybe make it raise the user's Defence by two stages and not just one.
Whirlpool

 

[CynthiaLover]

Increase its accuracy to at least 90%, as it's too unreliable otherwise.

Thunderbolt

 

[Camille]

Make it a 95 base power attack once again.
Hyper Fang