In his opening statement to the jury, Mr Paino said Waipuka accepted he punched Mr Cottrell in the jaw once.
Mr Paino today acknowledged his client was in a "troublesome" mood the night Mr Cottrell was killed.
"Waipuka punched a man and then ran up the road and told people ... and thought it was a bit of a joke," he said.
"I acknowledge that the client that I represent would not ordinarily be deserving of an ounce of understanding," he said.
But he implored the jury to look at Waipuka's maturity when deciding whether he had murderous intent.
"There's a general theme of immaturity running through [both] the accused."
Paino said Waipuka made a "simple straight punch at head height".
"There were not three kicks, the defence's case is that there were no kicks but it was added on by the accused (when talking to friends and family)."
Waipuka added on statements about kicks because he was showing off and getting carried away.
"(He is) an immature man with a warped sense of humour," said Paino.
Following two weeks of Crown evidence, lawyers for Waipuka and Robinson did not call any witnesses to give evidence.
Mr Cottrell was rushed to hospital after being left with broken bones and a shattered skull in an attack on a central Wellington footpath early on December 10 last year.
He died in hospital the following day.
In the Crown's closing argument, prosecutor Grant Burston told the jury that Waipuka and Robinson did not need to have inflicted the fatal blow to have been party to the murder.
"The Crown says both accused were involved in the beating ... whoever it was who inflicted the fatal blow."
The evidence, when considered together, meant both were involved in inflicting blows that contributed to Mr Cottrell's death, Mr Burston explained.
Mr Burston this morning said the attack was "completely unprovoked", leaving Mr Cottrell's head and body broken.
"It is clear there were only two other people present on Boulcott St at the time Mr Cottrell was attacked."
Both accused were aggressive to others before the attack, and both made admissions to being involved in the attack on Mr Cottrell.
"The Crown says that what the two accused did to Mr Cottrell is murder. You may feel sorry for one or both of the accused ... you may feel pity for Mr Robinson that he has club feet and didn't do well at school. However, feelings of emotion ... have no place in a murder trial."
Robinson's lawyer Mike Antunovic said the Crown failed to prove ``by a country mile'' that Robinson was guilty of murder or manslaughter.
He did not commit murder because he was on the other side of the road at the time of the attack, Mr Antunovic said.
Robinson saw only part of what happened, and did nothing to encourage or provoke the attack on Mr Cottrell.
Mr Antunovic reminded the jury that for the accused to be found guilty, it had to be beyond all reasonable doubt.
"If you're left with an honest and reasonable uncertainty ... then you must find him not guilty,'' Mr Antunovic said.
"I don't ask you to like Manuel Robinson, but I do ask you to give him a fair go.''
Mr Antunovic said the Crown's case hinged on 28 seconds when the attack could have happened, based on CCTV footage.
"Any assessment of this evidence clearly supports the defence case. It clearly established that Manuel Robinson could not have been involved in any incident with Mr Cottrell,'' he said.
"It's not possible, not if things were happening at a regular pace.''