FINAL FANTASY X/X-2 HD Remaster

The Alchemist dress sphere is acquired by helping Clasko open the Chocobo Ranch.

1. On your first trip to Mushroom Rock in Chapter 1, speak to Clasko before heading up.
2. Once finished at the Youth League HQ, run all the way back down and speak to Clasko again. He'll ask you if he can board your ship. Say yes.
3. Speak to him in the cabin.
4. Speak to him in the cabin again in Chapter 2.
5. After you help Callie with the chocobos on Mi'Hen Highroad in Chapter 2, speak to Clasko outside Rin's shop for him to get back on the airship.
6. When you go to the Calm Lands in Chapter 3, Clasko will run off. Choose to follow him.
7. You'll end up at the ruins (remember monster catching in FFX?). Clasko will ask you to deal with the fiends.
8. Once you've cleared out the place, you'll receive the Alchemist dress sphere.

Now just use Mix thirty times.