The Blues, coached by Dale McIntosh and Lee Jarvis, finished this season top of the Under 18 Regional table with only one loss and a draw - both against the Scarlets - spoiling their record.
The Scarlets went down at home to RGC 1404 and recorded a further draw against the Ospreys but both sides are keen to make the final the match that counts on Sunday.
Following on from Matthew Morgan's impressive performance for West Wales U20 on Wednesday evening, the Scarlets, coached by Warren Leach, Josh Turnbull and Rob McCusker, have their own teenage outside-half sensation in Jordan Williams, while openside flanker Daniel Thomas is one to watch out for having won the player of the tournament for Welsh Schools Under 16 at the Four Nations in April and having performed consistently well all season.
The Blues have a strong pack, with the back row particularly impressive, especially captain Ellis Jenkins. They also have some dangerous backs with Cory Allen and Harry Robinson particularly potent.
"This is the culmination of a lot of hard work all season and we want that to come together in a good performance on Sunday," said Blues head coach McIntosh.
"The Scarlets are our bogey team and, having failed to beat them this season, we certainly don't underestimate them, but this is the match that counts and if we can pay attention to detail and take our opportunities, I know the boys are determined to do well.
"I've been to a few finals with teams with the favourites tag but who have come out on the losing side too and for that reason, we will give the Scarlets all the respect they deserve.
"All the boys are very professional these days and I'm looking forward to the match on Sunday to see what they can produce."
WRU Performance Programme Manager Kevin George said of the Scarlets: "We were very disappointed with the result of the final last season, especially with the calibre of players we had in our side like George North, but hopefully we can put that right on Sunday on a fast St Helens pitch.
"We are always there or thereabouts in this competition, but it would be good to lift some silverware again after missing out for a few of years."
Wales Under 18 head coach Gruff Rees has delayed naming his initial training squad of 50 players until after this game and is keen to see how players react under pressure.
"It's always good to see how players perform under the intensity of a final, to see if they are able to step up to the next level," explained Rees.
"After Sunday's game, we will invite 50 players to come in for four sessions throughout January, working on skills and with off-the-field workshops before we narrow the squad down to 32 for the international season."
WRU Under 18 Regional Championship Final: Sunday 9 January, 2pm, Scarlets v Blues, St Helens, Swansea. There is free entry to this game.
Dylan Morgans (Coleg Sir Gar/ Lampeter); Jake Randell (CSG/ Scarlets), Steff Hughes (vice-capt, Ysgol y Strade / Llanelli Wanderers), Gareth Owen (Preseli / Narberth), Aron Evans (CSG / Scarlets); Jordan Williams (CSG / Scarlets), Conner Lloyd (Preseli / Scarlets); Gareth Thomas (Dyffryn Teifi / Newcastle Emlyn), Tom Ball (capt, CSG / Scarlets), Tom Kaijaks (CSG/ Pembroke Dock Quins), Dyfed Morgan (Newcastle Emlyn), Carwyn Jones (Sir Thomas Picton / Haverfordwest), Chris Marks (Dyffryn Teifi/ Carmarthen Quins), Daniel Thomas (Ysgol Bro Myrddin/ Scarlets), Jonathan Williams (Ysgol y Strade/ Kidwelly)
Jake Ilse (CSG / Narberth), Brandon Allsop (Llandovery Coll), Tom Evans (Bryntirion/ Maesteg), Llewelyn Jones (Sir Thomas Picton / Haverfordwest), Rob Jones (Llandovery Coll), Owain Powell (CSG/ Scarlets), Nico Setaro (CSG/ Whitland), Panashe Rushesha (Llandovery Coll / Bonymaen)
Richard Lovering (Christ College Brecon / Llatwit Fardre); H arry Robinson (Kings Mongton School / Blues), Ryan Evans (Tonyrefail Comp /Tonyrefail), Cory Allen (Ysgol Gyfun Bro Morgannwg / Glam Wands), Owen Jenkins (Pontypridd High / Ynysybwl); Rhys Pratchell (Ysgol Gyfun Glantaf / CRICC), Luke O'Brien (Corpus Christi High / St Joseph's); Thomas Davies (Ferndale Community / Ystrad Rhonddda), Jack Dando (Coleg Morgannwg / Ystrad), Brad Thyer (Ferndale Community / Ystrad Rhondda), Ben Roach (Llanishen / Llanishen), Chris Lacey (Ysgol Gyfun Cymer / Treorchy), Jordan Sienawski (Bridgend Coll / Blues), Ellis Jenkins (capt, Bryncelynog / Blues), Lewis Young (Coleg Morgannwg / Blues)
Jac Hopkins (Ysgol Gyfun Glantaf / CRICC), Callum Lewis (Coleg Morgannwg / Aberdare), Jack Dunning (Coleg Morgannwg / Treorchy), Luke Connolly (Coleg Morgannwg / St Joseph's), Simon Pring (Llanhari / Llanharan), Joel Raikes (Coleg Morgannwg / Rhydyfelin), Jack Phillips (Radyr Comp / St Joseph's), Lloyd Chalke (Stanwell School / Glam Wands)