Yes TM both if u have the TMs to do so. I don't see double dragon gyarados as that useful going forward because vs dragon, ice or dragonite (soon salamance too) will be much better.
And definitely get a SE golem while you can and be safe. It's his best charge move and very useful vs a lot of legendary Pokémon. Would not be surprised if many returned kuz I don't see gen 3 legendaries coming anytime soon.