What should I improve on my pokemon for pokemon diamond? Im stuck on the elite four?

Question

I have a lv. 54 Torterra that knows earthquake, wood hammer, giga drain, and synthesis, lv. 46 Luxray that knows Thunder, Thunderbolt, Charge, and Crunch, lv. 44 Staraptor that knows Fly, Steel Wing, Close Combat, and Aerial Ace, Lv. 34 Rampardos that knows Brick Break, Sanstorm, Earthquake, AncientPower, Lv. 36 Gastrodon that knows Surf, Waterfall, Mud Bomb, and Body Slam, lv. 48 Dialga that knows Metal Claw, AncientPower, Drangon Claw, and Roar of Time.

Answer 1

It's simple. Level up more. To at least have a half decent chance all your pokemion must be at least lvl. 60.

Answer 2

All You Need To Do Is level your pokemon up. you cant rely on one or two pokemon to carry you through which that seems like the case here. You need to get them to level 60 or higher. I made it through with mostly level  60 pokemon.

Answer 3

make your pokemon level 70-80 at least.