Winner
Diverse in Unity
They would win air superiority through sheer numbers and with that comes the ability to clean the seas of the enemy. Naval superiority over such short ranges is not necessary if you have air superiority, as they would.
How could they win air superiority?
Even if Japan stayed neutral, which is very likely, China would have to destroy the combined Taiwanese-US airforce.
That's not possible. Most of Chinese fighters are old Russian Mig-21's, even Mig-19's (utterly obsolete). Yes, they plan to build more of their new J-10's and they plan to buy some new fighters from Russia, but in the near future (10 years), they won't have anything what could pose a seriouse threat to the US-Taiwanese air forces.
You know, in such situations, numbers don't matter. You can have 20 Mig-21's against one F-22 or Eurofighter and they won't shoot it down. This is not Civ, spearmans don't beat tanks in the real world. You can have hundreds of obsolete fighters but it won't do any good against handful of hi-tech fighters.