No such requirement in RosaryHill pre-nursary (2-year-old) class. My girl has been studying there for a few months before she quitted pampers recently. Before that, the school just requested us to put some pampers in her school bag. The school will keep them in the classroom for changing.
There should be no such requirement, my daughter was still wearing diapers when she starts pre-nursery and the teachers help to teach them. She doesn't need to wear it to school after the first 1 or 2 months.
Before my girl attended nursery last Aug, school already informed us no need to quit the diaper, as they will train them to go to toilet which I very much appreciate. At the end, the school only spent 2 weeks and successfully quit the pampers for her.