Not sure I follow, but what I think you're asking is: is Ricky the only factory pilot of a CR250? i'm hardly and expert, but here's my rundown...
Answer: No. Fonseca is on a factory CR250, and LaRocco's bike might as well be a factory bike, even though he rides for his own team... supposedly gets factory parts.
Kawi only has one factory 250 guy: Lusk.
Yamaha has many: Reed, Vuillemin (sp??), Ferry (4-stroke), and probably others I forget off-hand.
Suzuki started out the season with three guys: Tortelli, Pastrana, and Roncada... but only Roncada is riding b/c the other two are hurt.
So really, Kawi is the one that started out being out-numbered there. The Pro-Circuit team is a Kawi support team, though I just read an article in another mag that says that their bikes are every bit as good as the factory stuff.
I imagine you see a lot of privateer Yamaha's b/c they're arguably the best bike to start with... consistently rated the top one or two bikes in most shoot-outs... either 2stroke or 4stroke. And no, I don't have a YZ, I have a KX... just reporting what I read
I made it to the Dome, had a great time. I came away with a new respect for Chad Reed. He really is capable of running with RC. During the early laps of the 250 main, RC was chasing Lusk, and Reed was in 5th or so. Most people, including me, were watching RC slowly but surely reel Lusk in, and all of the sudden, Reed in on RC's tail, out of nowhere! Then the crowd was treated (it was worth the $37) of about 2 laps of Lusk, RC, and Reed running 1-2-3, battling it out. There was a buzz in the air you could feel. Everyone was hoping for another 15 laps of this great battle, but Reed crashed twice, and RC finally got by Lusk and very slowly but surely pulled away. Reed didn't seem as fast after he crashed twice. Too bad for us. I think RC knows he's going to have to up his game a little this year if he's going to hold off Reed consistently.
Stewart is on a factory Kawi, just the wrong size. Pound for pound Kawi has the most successful factory team out there. Lusk is a definitly one of the top 5 in 250's and stewart will be one of the top 3 when he switches next year. (Stewart rules the 125's). Hey, it is also nice to hear someone else is on a KX. Green sticks out like a sore thumb amongst all of the red and blue bikes. My friend never have trouble finding me.
I think reed is tghe only one who has a good chance of knocking off RC but he needs to learn how to go fast without crashing.I really like Lusk and Ferry but I dont think either one has the skills of RC and the staying power to knock him off.If Stewart goes 250 next year things could be interesting