Formation Flying

I wonder if any of the pilots on here can tell me, what qualifications (if any)
are need to be able to take part in public displays when flying in formations ?

I remember one of the Breitling pilots saying on the TV, that it needed a fair
amount of skill, to fly different types of aircraft in a tight formation, as they all
had different characteristics.

I only ask this out of interest, and have no “agenda”