"They just have to turn up on the day and they will be alright," Tofa said.
"The titles are there for anyone to take."
The last local boxer to hold a national title was Tofa's son Viki Tofa, who now plays as a prop for Steelform Whanganui.
Oldehaver, a super-heavyweight, will be competing in the elite category.
"He's got a really good chance of making the final," Tofa said.
"There will be three fights before that, though. There's some tough competition, and it's mentally tough as well."
Preliminary bouts for each boxer, which last three rounds, are usually spaced at least 16 hours apart.
Tofa said Palmer had taken a break from the sport but was "back and rearing to go".
"Chille is one to be reckoned with in his division. I think there's a good chance he'll take it out.
"For Tekahui, there is only one other person in her division. They both go straight through to the final. Anything can happen."
Parkes is also going straight through to the final, facing Brooke Miller from Wairarapa.
"Brooke is from a boxing family in Masterton and she's pretty good. Isabella will have a lot on her hands.
"In saying that, they have already fought a few times and Isabella is getting very close to winning. It was only that last round where she lost."
As for Apiata-Cook, he will face a preliminary bout in the cadet division before potentially reaching the final.
"They've done the hard work. The rest is up to them," Tofa said.
"At the end of the day, they've just got to do their best. That's all you can ask for."
The team warmed up for the nationals with a tournament at the River City Boxing Club last weekend.
While numbers were down from previous competitions, there would still be between 130 and 150 boxers taking part next week, Tofa said.
"Canterbury are sending 25-30, and Auckland have a busload coming down.
"It's the pathway to that next level, whether it be Commonwealth or Oceania. You've got to have the New Zealand title under your belt first, though."
Due to current Covid-19 restrictions, no more than 200 people are allowed inside Jubilee Stadium at any one time.
"Only the boxers who are part of that particular session will come in, which means spectators can also come and watch," Tofa said.
"Each boxer is allocated three tickets to give to their friends or family who can come and pay at the door."
Tofa said he was "beyond excited" to finally host the event.
Whanganui mayor Hamish McDouall is lined up to speak and lighting will be supplied by Fergus Reid, technical lead at Whanganui Venues and Events.
"Sky (TV) will be there to cover the finals as well," Tofa said.
"There's a lot of stuff to do, but I can't wait."
The New Zealand Amateur Boxing Championships run from April 19 to April 23 at Jubilee Stadium.