Celsius
Before you head to the next destination to start Chapter 2, there’s a short interlude that takes place.
Celsius
You can’t do anything just yet until you head down into the bridge and speak with Shinra to examine the sphere. Ask him how the sphere analysis has gone. Say “yes” when he asks if you want to have a look. You’ll receive 
Al Bhed Primer after the video has concluded.
Afterward, speak to Brother for another scene. The team will decide to give the sphere back and do some dancing! Head back to the cabin and speak to Barkeep. Tell him that you’re singing tonight, and he’ll ask you to push the three musicians standing in the hallway into the elevator. It’s as simple as it sounds: have Yuna slowly walk into each one to push them across the hall. If one gets stuck, talk to Barkeep again to reset them.
There are a few more cutscenes before Yuna wakes up in the cabin again. Head down to the bridge and speak to Brother one more time. Now you’ll have to decide who to return the Awesome Sphere to: either Youth League or New Yevon.
Warning
This decision is critical, and a point of frustration for many people who played Final Fantasy X-2. This seemingly innocuous and unimportant decision has huge downstream implications, not in terms of the story or the actual events of the game that unfold, but in determining whether you’re able to get 100% Story Completion.
- Selecting New Yevon gets you access to additional items, access to some shared items earlier, access to an additional Mission, and earlier access to some dungeons.
- Selecting Youth League gets you more story.
And since players are typically going for 100% Story Completion, you need the route with more story. In fact, it’s only possible to get 99.2% Story Completion if you select New Yevon.
Why is it set up this way? It’s difficult to say, but what’s clear is that more story elements are built into the Youth League side. The developers likely intended for players to try one side for a normal playthrough, and then pick the other side during a New Game+ playthrough, but that’s not officially confirmed. What is confirmed is the choice you need to make between the two factions:
Select Youth League (Mushroom Rock Road) if you want to get 100% Story Completion!
But… before you make your selection, you finally have control of Yuna on the Celsius. You can get three important tasks out of the way, right now!
- Open up all the treasure chests down here in the engine room. This time they contain eight
Potions, five Phoenix Downs, four Remedies, and two Ethers. - Have Yuna rest in the cabin again.
Resting now awards nothing on its own, but the Chapter 5 scene it unlocks is worth 0.4%, and it only plays if you rested in every chapter.
- Obtain the
Psychic Dressphere. This Dressphere was added in the HD Remaster version of the game, and all you have to do is win the “Standard Cup” Tournament in the Fiend Arena of the Creature Creator. This tournament is very forgiving, and you can try over and over again with no repercussions until you get it. Check out the Creature Creator section of the guide for more information.
Dresspheres
The Psychic is an extremely strong Dressphere, to the point that it can almost be considered overpowered if you get it early on in the game. Either way, it’’s a Dressphere worth having, because the abilities your party members gain through it are strong from the moment you equip it.
Speak to Brother and select your location. As a reminder, most players will want to select “Youth League” by going to Mushroom Rock. Another lengthy set of cutscenes will take place as Yuna hands over the Awesome Sphere. Save your game one more time, and then it’s time to head to the first Mission down in Besaid.
Which faction did you select?
Checking the “Celsius Complete” box adds the Story Completion Percent for the automatic scenes in Celsius.