What is a group of coachs called?

Answer 1

If they're motor-coaches (single-level passenger buses) a group would be called a 'fleet', as with any group of motor vehicles.

Possibly you could use the term for horse-drawn carriages as well, or the term 'train' would also apply there.

If you're thinking of people who coach, or train, sporting teams, students, and people needing instruction that might be referred to as coaching, they'd be categorized as 'teachers'; there isn't a collective noun for teachers, though quite a few ideas have been offered on the subject: a 'pedantry' of teachers, an 'enthusiasm' of kindergarten teachers, a 'creak' of retired teachers, a 'huge groan', or possibly a 'terror', of teachers approaching their first class of adolescents...

Maybe you could consider the sport or other pastime or work involved in the coaching you want to collect coaches for? You could have a 'troupe' of drama coaches, a 'wicket' of cricket coaches, a 'splash' of swimming coaches, a 'designer boutique' of tennis coaches, a 'nineteenth hole' of Golf coaches, a 'rattle' of tap-dancing coaches - think about the subject your coaches are coaching and you'll surely come up with some great ideas.