Realize that if you're going for easy recognition, it's not just about color but about style. (meaning primarily design, though it never hurts to have style
)
Yes, there are dozens and dozens of teams with black t-shirts, or blue t-shirts, or yellow t-shirts, or purple t-shirts, etc--but they're all t-shirts. That's not to say you can't be distinctive in t-shirts: big logos, metallic/shininess (<3 MOE), though especially with distinctive colors can definitely set you apart. No ones confusing MOE or Thunderchickens with anyone else, or even each other! Though 365 especially is green from their bow ties to their wire ties.
Still, if you're looking for another trick, add something to the ensemble. The FIRST world is overflowing with black/white/red teams and red/orange teams, but most don't push it to flame or cameo pants (though some do; then life gets really confusing, <3 1511). Or rock out the ties, hats, socks, what-have-you--as long as it's safe.
Avoiding monochrome is also an effective way to get spotted. It's hard to lose track of
MORT's epaulets,
Bacon's sleeves (the colored sleeves),
WildStang's...WildStang,
Daisy's trim checkers (even understated, at least compared to WildStang),
or 25's shirts (well, at least in New Jersey), to name a few.
In short, don't just hunt for the color, hunt for the style. If you can stand 100-200 feet away from someone and still see the contrasting elements (both within their uniform and from the backdrop), you've got a good start.