I know nobody is really clear on the themed team rules yet, but I figured I'd post anyways. The Legion rulebook says -

"When all characters on a force share a single common keyword among the keywords listed on their character cards and the force consists of at least three or more characters and one character for each 100 points (or fraction thereof) in the build total, the force is a themed team."

Do bystander tokens count as characters on your force? Technically they have no keywords (as far as I know) and therefore no bystander tokens could be used on any themed team, but that doesn't seem right to me. The rulebook even says "A bystander token is a character represented by..."

I'm trying to build a legal Birds of Prey team (or I will be after JL comes out), with E Vixen, V Katana, V Manhunter, JL Black Canary, and JL Gypsy being the legal characters with the keyword, and coming in at a build total of 242 points. Obviously that leaves me with lots of room for feats and bystanders, so I need to know if I can use bystanders, or if I should just find 58 points worth of feats to throw in.

Yes, bystanders are characters, so no pogs on a themed team. Besides, that team's gonna NEED feats to stand a chance--!

Your probably right about that, but I still think it could be fun to play. Lots of L/C, Exploit Weakness, Stealth, B/C/F, and some Super Senses, Prob., and Defend with Gypsy. Add the right feats, it could be pretty competitive. Somebody suggested ICWO for 50 and Protected for 8, which makes it an even 300.

ICWO is retired as well, otherwise you could just add Oracle...
Anyway, I'd probably go with the following feats:
Pounce on Vixen and Manhunter for some first strike capability.
Swingline on Katana to let her make the most of her Batman TA
Running Start on Gypsy to keep her mobile
That's 45 points, putting you on 287. Vault on Manhunter might not be a bad idea, putting you at 290...

I would have to agree with you on this, but i would like to add something,throw in nano-bots for the last 10, not sure who on though.

Well, if you're looking to stick with the non-retired, Swingline was retired with the Icons set, so that one's illegal too. It'd be nice if they'd reprint that one though.

Oops, that one slipped between the cracks. That makes 20 points to fill out.
Manhunter maybe? She has good mobility with Leap/Climb, qualifies for almost the entire dial, and has Super Strength in there, so she's likely to be near objects anyway...