The Scarlets set the benchmark for the 2004–2005 season in winning all three finals at U16, U18 and U20 levels. WRU High Performance Manager Mostyn Richards said of the championships, “These competitions will provide the breeding ground for our national age grade players at U16, U18, U19 and U21 levels. All national age grade teams have extremely tough programmes this season and this competition will certainly help us prepare our players for the challenges that lie ahead.”

The U18 championship began on the same weekend as the thrilling U16 championship. The Blues met the Dragons at Sardis Road whilst the Ospreys hosted the Scarlets at the Talbot Athletic Ground. Having lost out to the Scarlets in the previous season’s U18 final at the Millennium Stadium, the Ospreys were desperate to avenge their defeat. Although they trailed on two occasions they came through to edge a thrilling contest 31-26; a brace for Tom Williams and solo tries from John Jones and Lloyd Elliott guaranteed the Osprey victory. John Davies gained a Scarlet brace with Daniel Evans and Rhys Williams adding other tries to the tally. Evans added three conversions for the visitors. Two penalties from Richard Cunniffe and a third from Leigh Halfpenny edged the Ospreys home, aided by the one man advantage due to a Scarlet red card, in a game that regional rugby director Dai Arthur described as “hugely entertaining”.

The U18 Dragons scored two tries in the game at Pontypridd courtesy of wing Anthony Brown and replacement scrum half James Leadbeater. However, the Blues helped themselves to double the Dragons’ try count and, consequently, their first win of the season. David Langdon, impressive with the boot in the previous year’s championship, added two conversions for the Dragons but it was the Blues, demonstrating greater strength and stature in their forwards, who gained the 27-14 win.

The second round of the U18 championship saw the Scarlets host the Blues at Stradey Park looking for their first win of the season following their opening round loss. The Scarlets just pipped the Blues to the 33-30 win as Daniel Evans and Josh Turnbull attained tries, Gruff Jones grabbed a brace and Evans added thirteen points with the boot. The Blues also scored four tries courtesy of Matthew Edwards, Rhys Dyer, James Toller and Tom Price with James Thomas kicking three points less than his opposite number. Meanwhile, the other round two match witnessed an Ospreys fightback to grind out a second win of the season, against the Dragons at Virginia Park. Richard Cunniffe continued his scoring form and slotted over a penalty five minutes before the interval, yet with only ten minutes remaining the Ospreys trailed 11-3 following a Gareth Dare try and penalties by David Langdon and Jason Tovey. As the Dragons’ victory looked secure Rhys Lawrence closed the gap to three points with the Ospreys’ first try and Leigh Halfpenny touched down three minutes later to secure the last-gasp spoils, 13-11.

The unbeaten Ospreys next took on the Blues as they searched for their third successive win in the competition. The other round three clash saw the Dragons host the Scarlets at Caerphilly’s Virginia Park. The visitors were 38-11 winners against the Dragons despite trailing 8-0 inside seven minutes, a penalty try and a penalty from David Langdon pushing the home side ahead. However, after a second Dragons penalty the Scarlets started the rout with a brace from Matthew Lemon and individual efforts from Rhys Williams, Matthew Evans, Justin James and Daniel Evans. At Sardis Road the Blues also recorded a high-scoring result as they hammered the Ospreys 35-3 at Pontypridd’s Sardis Road. This impressive display saw the Blues attain their second victory of the season whilst also halting the Ospreys’ opening dominance of the season.

Round four of the competition saw the Blues extend their successful form with a 23-12 success over the Dragons. The match at Abergavenny demonstrated the Dragons’ ineffective form as they had failed to get out of the starting blocks in the 2005–2006 WRU Reebok Regional Championship. The Dragons gained tries through Jason Tovey and Ceri Young with David Langdon adding one conversion but they could not overcome the Blues, who led 11-7 at half time. Three tries from James Egan, Sam Warburton and Hugh Dowden saw the Blues outscore the Dragons on try count with James Thomas making sure of the victory as he notched the extras with the boot. Though the visitors had a man red-carded they obtained the win despite their numerical disadvantage.

The Ospreys regained their winning form as they visited the Scarlets at Llandovery and secured a 6-0 success. Wing Leigh Halfpenny slotted a penalty whilst a drop goal from replacement outside half Tom Cole doubled the Osprey score. Daniel Evans missed three penalties for the Scarlets but had an outstanding game as did centre John Davies and Osprey scrum half Rhys Webb. The Scarlets were looking to avenge their season opener defeat to the Ospreys but after they had received a thumping by the Blues in the previous round the Ospreys clung onto the narrow advantage to recapture their successful season.

The Blues hosted the Scarlets in round five, seeking retribution for their earlier 33-30 defeat in the season. They achieved their revenge with a win at Sardis Road and with the Ospreys doing the double over the Dragons at Aberavon's Talbot Athletic Ground there was all to play for in the final round. The Ospreys, Blues and Scarlets were all tied on seventeen points at this crucial stage in the championship with the Dragons firmly rooted to the foot of the table with only two bonus points resultant from their five losses. The finalists for the U18 championship would go own to the wire as the Blues took on the Ospreys and the Scarlets faced the Dragons.

The Ospreys concluded their impressive pool stage with a 15-3 triumph at Aberavon. Jonathan Jones and Rhys Lawrence scored tries for the Ospreys as they took control against the Blues and with Leigh Halfpenny adding a conversion and penalty the home region booked their place in the U18 Reebok Regional final. Ospreys Regional High Performance Manager Dai Arthur commented after the win, “we are absolutely delighted. We have played well all season and with the exception of one game I think we can be proud of the way we have played. It would be nice to think we can go one step further and win the final. I think the boys deserve it."

The Ospreys would meet the Scarlets in the U18 final, as they saw off the Dragons at Llandovery in the last pool game. The Scarlets scored three tries in their 22-13 defeat of the Dragons: Josh Turnbull, Daniel Evans and Jamie Charlton all secured scores as the Dragons, in a contrast to the successful U16 side, went down to their sixth defeat in six games.

In a re-match of the previous season’s final the Scarlets aimed to retain the title they had won in the initial U18 Reebok Regional Championship. Meanwhile, the Ospreys would be desperate to avenge their previous final defeat at the hands of the Scarlets which they had lost a year ago.

The Scarlets took an early lead after nine minutes courtesy of a try from scrum half Justin James, but Leigh Halfpenny reduced the red advantage with a penalty midway through the first half. Daniel Evans, one of the championship’s best players of this season, improved the Scarlet lead with a penalty before the Ospreys went ahead; a try from prop Ryan Bevington together with Halfpenny’s conversion provided a slender 10-8 interval lead. The Ospreys continued their scoring form after the break as the Scarlets failed to register a single point, consequently relinquishing the championship title they won at the Millennium Stadium last season. Halfpenny added a penalty to take the Ospreys’ lead to 13-8 before Luke Hathaway secured the win with a converted try in the final quarter. Coach Phil John commented after the win, "We are absolutely delighted for the boys. They have worked hard all season to reach this final and they worked hard on the night to win it. It was a determined, tenacious and tactically aware performance."

Following in the footsteps of the Scarlets in the inaugural Reebok Regional Championships, the Ospreys had attained a clean sweep in the 2005–2006 season throughout the three age grade competitions. The season saw further success for age grade rugby as Wales U19, consisting of players from the four regional U20 sides, won a grand slam in the U19 Six Nations championship in March. Many of the U20 players also travelled to Dubai for the IRB U19 World Championship in which the Wales U19 team finished in sixth position.