Act Party leader David Seymour is confident his new caucus members are up to the challenge of being MPs.
Act got 8 per cent of the party vote, giving it 10 seats - its best-ever election result.
Seymour says his MPs bring a vast range of experience to Parliament, including former police officers, environmental engineers and farmers.
Seven out of Act's 10 MPs are small-business owners, he says.
"There's a challenge of course for me leading that team and I want to meld our caucus into a very high-performing organisation and of course for them, Parliament is a bit of a weird place sometimes, and there'll be a few ropes to learn but I'm very confident they can do it."
National's election result was lower than suggested by the polls, which was a surprise, he says.
"I guess the important lesson is that you have to be constructive, you have to stand on principle when it matters and those are the things that I intend for Act to do."
He says it is a very difficult situation globally and many countries are having a tougher time than New Zealand.
"That doesn't mean we shouldn't be making positive and constructive criticisms when applicable and also calling them out and asking the right questions when necessary."
Seymour says an opposition party has two roles - it needs to ask the questions people want asked about how taxpayer's money is being used.
"Secondly to come up with an alternative competing vision for how New Zealand can be so the voters at the next election have choice and you'll certainly see that from Act on both counts."
Seymour says Act was "able to run quite a well-oiled campaign" because a lot of people have been involved in building the organisation over the past six years.
He says it is good to be able to welcome nine new MPs to Act.
"The caucus of a political party is really the tip of the iceberg, but I'm glad that that tip is finally growing a bit."
Seymour 'charted a course' and 'stuck with it' - John Banks
Former Act leader John Banks says Seymour is a stand-out performer and his strategy of "staying on message" has paid off.
"I think it's extraordinary and without a doubt he's the best performing member of Parliament after the Prime Minister."
"He charted a course and he stuck with it, he went out to the public stayed on message, in volume over time ... but to counter balance that the National Party were in melt down all of this year and so were the New Zealand First Party, so David was able to scoop up all that disenfranchised support for those two parties."
Banks says Seymour worked in the parliamentary office as his speech writer, so he knows him quite well and describes him as very hardworking and smart.
"There's been also a sharpening up of David incorporated when he gave up drinking and decided to get really fit."
Banks says in a small party the new MPs will have to hit the ground running and he advises them to stay with their disciplines and engage with what they know, but also to hold the government to account.
"Because the National Party don't have the depth and don't have the quality and don't have the boogie to hold this huge Labour caucus to account."
Seymour should talk to National about strategy, but he will need to define his own path in the future, Banks says.