The name Sextet Pistols is a play on the six piece combo group being called a sextet, combined with the idea of the Sex Pistols.
Ms Kulasingham encouraged other women to have the confidence to get into jazz.
"Just give it a go, and have fun," she said.
The band also consists of Tina Jeong, 16, on trombone, Bianca Goyena, 16, on guitar, Kayla Ross, 15, on drums, Darrel Nitschke, 16, on vocals, and Anna Scherrer, 17, on tenor saxophone.
Director of National Youth Jazz Competition Liam Ryan said bands had come from all over New Zealand, from Kerikeri to Christchurch.
"It's truly a national Jazz Fest," he said.
"What we are seeing is a deepening of the skill level and understanding of jazz by school music students. If jazz is about breaking down barriers then the National Youth Jazz Competition epitomises that."