[4] During the early part of 1999, Koopu played for the Glenora Bears and represented Auckland North.

[5] While contracted to the Warriors, Koopu also played in the then feeder clubs for the NRL franchise, the Wynnum Manly Seagulls and the Newtown Jets.

Koopu played for the New Zealand Warriors from the interchange bench in their 2002 NRL Grand Final loss to the Sydney Roosters.

That year Koopu again played for the New Zealand Māori in two games, including a match against an Indigenous Dreamtime side.

[2][8][9][10] Koopu was named as reserve for the Storm team that won the 2009 NRL Grand Final,[11][12] a premiership that was later stripped after their long-term salary cap breaches came to light in 2010.