From the squad which reached the quarter-finals of the Rugby World Cup Sevens staged in Moscow in June, Cardiff's Gareth Davies and Llandovery's Adam Warren drop out while Iolo Evans (Carmarthen Quins), Sam Cross (UWIC) and Wil Thomas (Cardiff) come into the squad.
Due to the World Cup, Wales's pre-season preparations have been reduced but John says his squad go into this week's opening tournament in high spirits after beating South Africa twice in the Middleburg Sevens to win the title at the invitational event.
"Selection has been very hard and very competitive - a lot of boys have just missed out which keeps pressure on the group which has gone and it's great that we now have competition right across the squad," he said.
"The 12 boys in Australia are the guys who have put their hand up for the first tournament and the boys who have missed out will get another opportunity to impress before the next set of tournaments in Dubai and South Africa next month.
"Adam is the only new player and he has earned his spot. He took part in the GB Sevens series in the summer with our development group where he impressed playing centre and wing. He then came into our core group and he figured in Middleburg where he played two games against South Africa and once again did well - so he deserves his place in the squad."
John is hoping his team have learned some harsh lessons from last season's tournament in Australia where a defeat in pool play to Argentina was enough to miss out on a quarter-final after wins against Portugal and France.
"We won two games in the group but missed out on points difference - that was difficult as it happened three times in the season. It rams home the point that every game is massively important and every point is massively important and hopefully we have learned from that. This weekend we play Portugal, Canada and Fiji. That is a very competitive group and teams are only getting better so our main focus this week is to get out of group."
Wales Sevens squad for Gold Coast Sevens: Skilled Park, Oct 12-13
Adam Thomas - Capt (Pontypridd)
Rhys Shellard (Pontypridd)
Alex Webber (Pontypridd)
James Davies (Scarlets & Carmarthen Quins)
Lee Williams (Carmarthen Quins)
Iolo Evans (Carmarthen Quins)
Sam Cross (UWIC)
Alex Walker (Cardiff)
Will Thomas (Blues Academy & Cardiff)
Rhys Jones (Cross Keys)
Adam Field (Bridgend)
Chris Knight( Scarlets & Llandovery)