The perfect mma rules...

I would go with either no time limits or at least significantly longer rounds that allow a fight to develop more and push a fighters gas tank to the very edge.

the yellow card system for fighters that deliberately stall.

Kicks to a grounded opponent,headbutts and grabbing the cage all allowed as well as more leniency towards what fighters wear into the ring.

All champions must defend their belt 3 times a year.

Good start except for grabbing the cage.

jpm995 - Good start except for grabbing the cage.
Grabbing the cage sounds OK, until someone gets a finger ripped off, then you've got a media shit storm in your hands.

I liked the round lengths in Pride, 1 10 minute and 2 5 minute rounds.

Yellow cards for sure.

Kicks and stomps on the ground without a doubt.

Unsure about headbutts.

I also think elbows should be legal from any angle.  Screw this, you can't come straight done, you have to come at an angle.