Does my brother have a wrongful termination case?

Nope. Businesses need very little reason to fire someone. Only if your brother were part of a protected class would they have to be careful about how they fire him.

The best he can do is claim that he wasn't fired for cause and collect unemployment until he finds another job.

This wasn't wrongful termination.

He wasn't fired because of his race, gender, religion, sexual orientation, disability, etc.

He is an at will employee. This means they can fire him for any reason or no reason at all. Your brother did not handle himself properly or professionally - even if the other employee shouted at him, this was no excuse for your brother to shout back. (The smart thing for him to have done would have been to shut up and LEARN. You and I both know that he mouthed off, right?)

He was a new employee - which means he has very little value to the company. The other employee is obviously much more experience - which means the company is going to be more inclined to keep him.

If your brother believes he was physically assaulted, he can certainly call the police and make a report. But the employer has the absolute right to decide who works for them and who does not. And they can certainly cut his hours. (The fact that he was foolish enough to complain and threaten to get a lawyer over getting his hours cut would have caused me to fire his a$$, too.)

If I were you, I would tell your brother that he needs to grow up and shut up. He isn't entitled to a job. And he isn't entitled to a good boss. If he wants a job, he needs to learn how to behave like a competent professional not a mouthy kid.

The manager did nothing because he agreed with the other employee. And, since he was fired back at the other store, he just did not get it right. Otherwise, he would not have been fired. It is not a dangerous place to work, just because another employee grabbed him by the shirt and, they yelled at each other. It was a heated dispute. You cannot say the manager did nothing because that is not true. He transferred your bother back to the other store. Unfortunately, that did not work out either. Employers have a right to terminate anyone they feel is not learning quickly enough, is not fitting in or, for any number of reasons. Working at any particular establishment is NOT an entitlement and the employer has the exclusive decision about who he wants to keep and who he wanted to get rid of. The other guy seems to know the job better.

No, he doesn't.

He didn't have a contract, wasn't part of a union, and wasn't fired for a discriminatory reason.

You can't sue simply because it seems unfair. The employer gets to decide who they want to keep when two employees don't get along.

No. Since he is working without a contract, he is considered an at-will employee and can be legally fired for any reason or no reason at all. Employers do not have to be fair.

grounds for netting $30k from the co.