I want teach Dark Pulse to my Helioptile to defeat the Psychic Gym (that's in the faar future, I have 4 badges), but if I finished the game, should I keep it?
The other 3 moves I planned are:
In fact, you should keep Dark Pulse over Bulldoze.
A good in-game set is:
Bulldoze is bad idea due to Helioptile's low attack stat, and high speed in general. Surf or Dark Pulse are much better. As for Electrify, it's your personal choice, seeing as it may or may not be useful in battle.