"They have made a call for us to come together ... What we were prepared to do over the last six to eight months was find a way to do that.
"It's about bringing about the return of the Maori seats to te kaupapa-based Maori parties. What we have done is what the people have asked us to do."
Mr Flavell said other parties had done similar deals in the past.
"The precedent has been set by every other party."
He said he would not be taking another win at this year's election for granted because Labour's Tamati Coffey, the only other Waiariki candidate so far, wasn't an unknown.
"But I'm confident with the team I have got behind me ... I'm looking forward to the campaign and I'm looking forward to hopefully bringing it home with an increased majority."
Mr Coffey said in his view the deal didn't mean Mana voters would vote for the Maori Party.
"After nine years in power the Maori Party has gone from 'independent voice' to a nodding head dog on the dashboard of the National Party. Today's deal does nothing to change that.
"Ineffective and ornamental, they have overseen our people becoming the stars for child obesity, mental health and education statistics for all the wrong reasons, while being locked out of dreams of home ownership and left to face rising medical costs, rents and rates of homelessness.
"I respect Annette Sykes, and her calls last election for a change in Government that will deliver for all Maori.
"For voters in the Waiariki who tautoko [support] that, it's officially a two-horse race. Labour is the only alternative and I will be your workhorse."
Mrs Sykes could not be reached for comment but previously told the Rotorua Daily Post she was positive about the relationship between Mana and the Maori Party as they were answering a call from elders and shared a common goal to remove Labour from Maori seats.
Te Arawa Lakes Trust chairman Sir Toby Curtis told the Rotorua Daily Post he thought it was a good deal.
"Whenever human beings agree to come together, no matter what the intention, you get a better outcome than when people come separate.
"What they have in common, helping the people perhaps who do not find living easy, will be better helped moving forward in the same intention and direction."
Mana Party president Lisa McNab said the partnership was a long time coming.
"Standing against one another only lets the party that stole our foreshore and seabed, steal our seats as well. We have to be better than that. Those seats belong to the Maori people, not to anyone else."
The Mana Party's leader, Hone Harawira, will focus on trying to win back Te Tai Tokerau from Labour's Kelvin Davis, while the Maori Party will stand candidates in the six other Maori seats.
Mr Harawira's defeat in 2014 meant the Mana Party ceased to have a presence in Parliament. Mr Harawira was a Maori Party MP until 2011 when he quit, accusing it of supporting government legislation that disadvantaged Maori.
He resigned from Parliament, formed the Mana Party, fought a byelection in Te Tai Tokerau and won.
- Additional reporting by Alice Guy
2014 Waiariki election results
-Te Ururoa Flavell (Maori Party) 9726
-Waititi Rawiri (Labour) 5837
-Annette Sykes (Internet Mana) 5482
-Pat Spellman (NZ Independent Coalition) 301
