I need to use a knee scooter for a handicapped leg can I bring it from BART to the Coluseum for an A"S game?

Yes, you can

Yes

Most certainly yes

Yes you shouldn't have any issue

I saw a person with one at monster jam

You shouldn't have a problem. They are wheelchair accessible.

All sporting events are set up for handicap people.. id say yes...

I believe so. They shouldnt fuss with such a thing