Outrage is the best charge move that Salamence can get that's in the game currently. Dragon Tail/Outrage Salamence will be one of the best dragon attackers in the game. However, that's only assuming Niantic will actually give it's best moveset. I'm fairly certain Meteor Mash Metagross was so good because Steel isn't really a good attacking type compared to dragon. Salamence could very well get Dragon Claw or Dragon Pulse instead.
If we're talking Dragon Moves that's not in the game, I think Dragon Rush has a very high chance of making into the game, and I'm quite confident that it will be a Gible community day move.