It would be significantly more difficult if the main plaintiff doesn't have personal experience on the issue. Not to mention a lack of evidence.
The best case they could make is "my son's friend says that another student knocked his phone out of his hand", which is uncertain at best.
Small claims courts don't have a full jury, the case is mostly done in pen-and-paper and the plaintiff settles 99% of the time shortly after receiving the court order.
You have to remember, these are courts that regularly deal with claims for a few hundred dollars to a maximum of a few thousand dollars. These cases cannot receive the amount of attention as cases you're probably familiar with learning about. These small cases are usually just decided by the judge after both parties present their opinions of what happened, and maybe some personal evidence they have.
