Koromatua, from Hamilton, were runners-up last year and strongly favoured again this season, while Flaxmere are the second best side in their grade in Hawke's Bay.
The week-long championship is New Zealand's largest junior sporting festival, attracting more than 7500 intermediate-aged students across 17 sporting codes this year.
WIS debuted at the games this year and is among 228 schools nationwide, a sharp jump from last year's 10th anniversary of the Games which boasted 193 schools and 6500 athletes. There are 36 basketball teams in four pools of nine, so the effort and skill to qualify for the quarter-finals is huge.
WIS coach Terry Tanoa was full of praise for his lads and said they had performed with distinction on and off court.
"On court the boys have played really good structured basketball and that's what's got them through - they've stuck to the game plans and I'm extremely proud of them all. The guys on the bench have definitely played their part too," Tanoa said yesterday.
"Our captain Kopere Tonoa has had an outstanding tournament so far as has Keilym Pari and Ngatoka Tua. And our bigs (tall players) Herewhetu Shelford and Kaea Cronshaw have really stood out. Off court they are the talk of the tournament too. The way they have behaved and especially the way they have represented and promoted Wanganui has gained respect here."
WIS deputy principal and part of the management team for the basketballers, Lisa Clark was also proud of the boys, but had special praise for her fellow management team.
"Terry's wife Tess and parents Mere Tua and Neihana Pari have played a huge part in making this a successful tournament. This is the first time the school has entered any team in the Aims Games and hopefully the success of the basketballers may pave the way for future teams," Clark said.