The two teams have spent eight weeks in training sessions and camps in Levin, Hastings and Taupo.
In the women's tournament, Central are the defending two-time champions, with Baker having received selection to the New Zealand Under 18 training camp at the end of 2018.
Her current squad with Redmayne is Hawke's Bay-heavy with eight players from that province, plus four from Manawatu and three from Taranaki.
Madder and Hoskin's team has a wider spread of the Central catchment, with six from Hawke's Bay, four Manawatu, three Taranaki, one from Horowhenua and the two Whanganui boys.
Last year, the Central Under 18 boys were in a very tough pool at their tournament, while as in 2018, the girls are picking Canterbury to be the other leading contender in their search for the three-peat.
Tournament week will be from Sunday through until next Saturday.
As well as national play, the Wanganui Under 18 boys team, coached by Robbie Matthews, will begin their regional tournament, also starting on Sunday.