I thought of this set:
Item: Wide Lens (to raise the accuracy of Iron Tail)
Abillty: Inner Focus
Nature: Naguhty (high Attack, low Special Defense)
-Iron Tail: Nice power + type coverage against Ice and Rock types and have a chance to lower the foes Defense.
-Dragon Dance: Attack bonus and helpful Speed.
-Ice Beam/Dragon Claw: Against other Dragon types.
-Thunder Punch: For all of those Flying/Water types out there (most of the Water types can learn some Ice type move so it is really helpful) and of course Paralyze chance (10%).
This set offer a type coverage set. It takes care of one of Dragonite weakness (his low Speed).
With Iron tail you wont need to worry about Ice and Rock types. If you use Iron tail after a Dragon Dance and while wearing a Wide Lens, no Rock/Ice types can even have a chance to touch you!
Dragonite got 1 more weakness- Dragon type. You can either get him Ice Beam or Dragon Claw and then with his high Speed and high Attack using the Dragon Dance you will beat any Dragon type in your way.
The last move was a hard choice. I wanted a move that will use Dragonite Attack and will help him against Water type especialy and maybe 1 more type coverage. Thunder Punch cover it all. Using Thunder Punch will not only kill Water types but Flying types too. It is a physical move that also have a Paralyze chance which makes it even more helpful in battle.
I chose the Inner Focus abillty because it is hard to get a Multiscale Dragonite and because having the abillty not to finch is better at this set because any finch means death here (because of his low Special Defense), but having no finch means that you can KO your enemy in only one turn, they wont have time to use a Special Attack move on you!