Hey fellow Final Fantasy X explorer! When it comes to sphere grid progression, focus on maximizing each character’s strengths. Use key spheres to unlock important nodes like abilities and stat boosts. Don’t be afraid to mix and match different paths to create unique character builds.

For side quests, make sure to complete the Monster Arena challenges for valuable rewards and tough battles. The Celestial Weapons are also a must-have for end-game content, so dedicate some time to obtaining them.

When it comes to character builds, consider specializing each character in a specific role like physical damage dealer, magic user, or support. Experiment with different abilities and strategies to find what works best for your playstyle.

Happy exploring and may the Aeons be ever in your favor!