Yeah I'm giving the Sphere to New Yevon. Why? A reason to do New Game+. (From what I hear if you hand the sphere to the Youth League. You can get 100% on your first playthrough I don't know about all that). Well main thing is to just talk to everyone. Not really a problem. Well to move on to your little party. You need to move our band players into the elevator. (make sure to open the chest in the engine room). This is just on the lines of annoying sometimes they'll end up pushed out the way of Yuna. Just push them into the elevator as best you can. When Yuna wildly jumps back you got one in. O'aka is here too (as well as Clasko). But I'll talk about this in a minute. I'll probably mention this again later.
After some R&R and nightmares, you're forced make a decision on whether you give the Sphere to the Youth League or New Yevon. The others don't really care who you decide. Just know whoever you give it to will block off some areas later.
Give Sphere to the Youth League:
-Kilika Port is blocked off.
-Bevelle is blocked off for the rest of Chapter 2 till the very end.You'll end up in a random mission where you try to fight your way in only to get booted out.
-A conversation is altered slightly later in Chapter 2.
-Lose out on a garment grid (you'll have to do New Game+ to get one or the other anyway)
Give the Sphere to New Yevon:
-Kilika Port is Blocked Off. (Conversation is altered)
-Mushroom Rock Road is slightly blocked off. (You're not getting into Youth League Headquarters.) You'll instead get a mission where you have to fight Youth League Members.
-In Chapter 4 you miss out on a couple of commsphere conversations.
-You apparently can't get 100% on your first playthrough.
-You lose out on a Garment Grid (You have to do New Game+)
-Youth League Headquarters is blocked off for the rest of the game.
-End of Chapter 2 is somewhat easier
Well. After your short party. You find that you got robbed by none other than the Leblanc Syndicate. "WHO'S ON TOP NOW DULLWINGS!"
So our plan is made. We're gonna take it back. Our mission is to find 3 fitting Leblanc Syndicate uniforms.
Well if you actually put effort into this. Be proud this pays off highly in the end. Any monsters you currently had with you will have there story levels ranked up Usually to max. This is cause they were with you at the end of chapter 1. Time to catch a new set of monsters. Fight at the arena, whatever. Just trust me when I say this becomes worth it later on.