How old do I have to be, and do I need to be a Pony Club member?

You must be 18 years old to be accredited as a Pony Club coach, although training can start from age 16. All Pony Club coaches must be financial members of a club, accredited riding centre, or state.

Source: Pony Club Australia, Coach Accreditation page, https://ponyclubaustralia.com.au/education-accreditation/coaches/.