Train drivers how to use a taser. Have every driver on a teenage school bus armed with a taser. Give him/her absolute authority to use during any and all altercations.
The ACLU and tame Federal judges will bankrupt school districts if that happens.
Put a teacher AND a parent on the bus and it MAY solve the problem....maybe.
Defang the ACLU and other scumbag tort lawyers then clean out the bench, bring back corporal punishment in schools and things might turn around.
Very early in life, while in public school, these thug learn that they will not be held accountable for their misdeeds.