what are the best moves for my salamance in pokemon diamond?

I suggest you add Dragon Dance.

Breed a female Bagon to a male Gyarados with both Dragon Dance and Hydro Pump.

For the moveset, check out smogon.com

I also have a Salamence, and here's its moveset:

Dragon Dance

Hydro Pump

Crunch

Dragon Claw

I'm still EV-training it, and I'm specializing on it's Speed, Attack/Special Attack.

Well, this set is just mine, and works well with Starmie with Rain Dance and Thunder. Powers-up Hydro Pump, and Dragon Dance will boost Dragon Claw.

Well, I've given you some of my ideas! Good Luck!

Hope I helped! :)

My recommended moves for you:

Hydro Pump

Dragon Pulse

Fire Blast/Flamethrower

Fly/Thunder Bolt

I would teach your Salemence a good fire-type move like fire blast or flamethrower because you can use it against ice-type pokemon. Since ice is super effective against both of Salemence's types (flying and dragon) it would be a strategic idea to defeat your weakness.

It doesn't matter whether you choose thunder bolt or fly. You can choose fly if you need a pokemon to fly you around Sinnoh. Or you can choose thunder bolt if you already have a pokemon to use fly.

I hope this helped. :)

if ur thinking of sp attack, then nice choice 4 ur salamence!!but change thunderbolt into flamethrower