When you first receive access to the Pokemon World Tournament, the Driftveil Tournament is the only one open to you. You must progress through the game before you can unlock more. To enter the Driftveil Tournament, head north to the two women standing between the two staircases.
Talk to the woman in green. You'll be presented with three options. The first is to let you enter into the tournament. The second is for further information about the World Tournament and how it works and the third is to exit the dialogue.
If you choose the first option you'd normally be given a number of choices about battle types (Single Battle, Double Battle, Triple Battle and Rotation Battle), but since you've only just unlocked the World Tournament, you can only select Single Battle or 'Exit'.
If you want to use different Pokemon, the PC next to the woman in red will allow you to grab any Pokemon from your PC Boxes.
Just as a heads-up, the PC next to the woman in green will present you with stats about your previous performances in tournaments, your current BP ( Battle Points , which can be exchanged for items) and will allow you to save your game.
Once Single Battle's chosen, select the three Pokemon you wish to use, confirm and the tournament will begin!
A few notes beforehand. The first time you challenge the Driftveil Tournament will differ to the subsequent times. This is the only time a Single Battle tournament will have trainers which have three Pokemon, including you. Normally they would only have two each.
Secondly, Pokemon participating in the Driftveil Tournament will automatically have their level set to 25 beforehand. This is true for all of the other trainers in this tournament, except for you. Yours won't change, whether they're above or below level 25, so keep this in mind.
Finally, experience or money are never earned from any of these matches, Pokemon aren't allowed to switch when they defeat an enemy Pokemon, you may not use items except for held items and your Pokemon are all healed in between matches.
If you lose during any battle, you don't lose any money but must restart the tournament from the beginning, but you will still earn a prize of some description.
Once you confirm and the tournament begins, you will first be shown the bracket. Check out who your first match is against... your rival! Also check out some of the other trainers entered in the tournament (Is that Cheren?... and Colress?). Before you realise, you'll be called up to fight your first battle!
Round 1: Pokemon Trainer Hugh
If Snivy was your starter
If Tepig was your starter
If Oshawott was your starter
Once your rival's defeated, the semi-finals will ensue. You will see Cheren, another trainer and Colress win their respective matches. You'll be up against Cheren next!
Round 2: Pokemon Trainer Cheren
Once Cheren's knocked out of the tournament, the other semi-final will be played out and Colress will win. It's time to fight him in the final!
Final Round: Pokemon Trainer Colress
Once Colress is defeated, the arena will go nuts celebrating your victory. You will then exit the area and head back into the lobby. You'll be congratulated by the woman in green and receive 1BP , which you can exchange for items!
Check out the Right BP Exchange Service Corner and Left BP Exchange Service Corner to see what's on offer. You will then enter a conversation with Hugh, Cheren and Clay. Roxie will also suddenly appear and suddenly disappear after she's said a few brief words.
Clay will then leave and you'll be free to do what you want. Unfortunately you can't enter the Driftveil Tournament again just yet. There's nothing left to do but leave! When you leave, Hugh and Cheren will follow you out and talk.
Suddenly, a New Team Plasma Grunt will bolt in from the west and sprint south into the docks. It will catch everyone's attention. Colress will then exit the PWT lobby and reveal himself as a member of New Team Plasma. Hugh will bolt after the Grunt, followed calmly by Cheren.
Colress will then say a few words to you and you'll be able to chase after the Grunt too. Head south into the docks. You'll see a boat which you'll be able to board. Do so. It's the Plasma Frigate !