Wheels for 200m standing start
 

As a part of an upcoming road race omnium, there is a "100-200m" straight sprint starting with a holder. Since this is more related to track racing, what type of wheels would you recommend? Deep dish(50mm TTish wheels), semi-aero 25mm rims, or light and fast accelerating wheels.

For any short full power standing start event I'd go with a disc wheel, which is the stiffest type you can get. They are a little bit heavier than a deep section sprint wheel with spokes, but not enough to have as much impact as flex. Aerodynamics are irrelevant here.

So, why would stiffness matter? Given that it's an acceleration game, wouldn't lower drive train weight matter? Especially considering that any rotating weight gets accelerated twice.

Given the distance, this isn't something that would be crazy to just test on your own. Get someone with a stopwatch, and give it a go.

+1 for testing, if it's really worth your while. I'd think that light rims would be way to go. I'd be tempted to find some old GEL 280s or even some older (and even lighter) wood-filled Scheerens.

OTOH, my old velodrome used to have chariots on a regular basis and, because they were just part of the omnium, it would have been considered silly to do anything special for them.

I second the light rims. Keirin racers in Japan use a wheel that has a light shallow tubular rim (like Araya), 36 spokes, and a high flange hub. Very stiff, very light.
Since its a standing start and a short race, you will only be going fast for a few seconds and won't take full advantage of an aero wheel. And you are not worried about saving energy, so a deep rim or a disc will be extra weight.