It shouldn't be a free-for-all, maybe something like:
Idea 1 wrote:Purple&Green team up vs Blue&Red
13+6=12+7
And then do Green vs Red and Blue vs Purple? Winner of the Winners is winner??
Idea 2 wrote:Green vs Red & Purple vs Blue
The best player leftover from the winning teams go head-to-head.(?)
Idea 3 wrote:Wisest thing to do would be to...
(hehehe, suspense.)
!!Ignore the ramblings of a questionably sane poster (I hang on a wall?)!!

Edit*Actually, it should be lowest number and other lowest number... not Green and Red, it's just they are currently the lowest.