any way to totally get rid of or greatly reduce the flicker on shots filmed at night, like at a basket ball court? Shooting 240 and 480 fps on FS700.

Would battery powered lights do the trick on the shoot?

Or in post any software to totally get rid of the flicker captured at those frame rates?

Depending on how bad it is you can use the BCC Flicker Fixer plugin.

The only way to get rid of it when you are filming is to use a continuous light source. A high frequency HMI can work at those rates. I would test before you rent a bunch of lights to do a shoot though.