Anyway, I had this idea for a fight the other day. It might or might not be super cool, but it would need some special rules. Here's the pitch. The players are either hired to work escorting a barge of supplies from one city to another in a large kingdom, or they are hired to stop the transport of the goods. Here's the twist. The "barge" is a ship that has been tied to the bodies of dragons in order to keep them afloat. Three in the front and three in the back and one on each side have been assigned to keep the barge going. The players either must fight on the barge or the dragons, or attempt to pilot their dragons in such a way as to then be able to board or fight on the barge or dragons.
It's not really that complicated. First, you have the general set up. No matter which side the players are on, the rules are the same. The barge requires two people, one at the front and one at the back to keep a handle on the dragons. Keeping the dragons under control and their speed constant is a minor action. To boost or slow their speed is a move action. To cause them to attack is your standard action. Only one dragon can attack at a time.
Here, the barge is brown and the barge dragons are green.
The exception to this is to allow a nature check to let a dragon act on their own. If they have taken no damage, the challenge is DC 10 + 1/2 CL. If they have taken any damage, the challenge is DC 15 + 1/2 CL. If the dragon is bloodied or worse, the challenge is DC 20 + 1/2 CL. Once you fail a nature check, the dragon acts on it's own from that point forward until their opponent is killed.
Now, you have enemy dragons, either the players or just plain enemies, incoming. They are blue. Piloting a dragon is the same as controlling a dragon on the barge. As you can see, the dragons on the barge are tethered at the start. You may leap from barge to the dragon and from dragon to dragon using the following skills:
Arcana - using a quick cantrip or manipulation of raw magic to direct the wind around you and buoy yourself (DC 14 + 1/2 level)
Athletics - you climb and jump across (DC 14 + 1/2 level)
Acrobatics - You tumble, leap and otherwise flip across (DC 17 + 1/2 level)
Nature - You speak with the dragon to extend a wing a bit and allow you across. (DC 17 + 1/2 level)
These skills may be used to aid others climbing across as well. While on a dragon, you must success a DC 10 Endurance check or be knocked prone, if you are attempting to cross or fight on one.
Now here, you can see the two parties start to meet. The blue team is opening themselves up to lots of attacks, but they are trying to enrage the dragons and free them from their tethers to make the boat more unstable and bring it down. The barge team is staying put and focusing fire on the dragons, hoping their riders will lose control.
Riding a dragon, you must succeed in an Arcana, Diplomacy, Intimidate or Nature check in order to keep control of the dragon once it enters combat. This follows the same rules as the barge riders letting the dragon act on their own. The difference is that you, as a rider, controls the actions of the dragon fully as if you were the dragon. Once you leave the dragon, the rules are exactly the same.
Now you can see the chaos start to unfold. One of the blue dragons has been downed, one of the green dragons has been downed, and three green dragons are off their ties. The ship, while not crashing, will slowly descend. The green dragons and blue dragons are going to be battling it out, so you better hope that the riders are safely on that barge, or are going to make their way there soon.
This is a high risk, high fun-potential battle that lets players control dragons to a limited degree as vehicles, before eventually becoming shipboard combat. It's not a perfect system or skill challenge, but it definitely has a lot of potential to be awesome.