Tidus' Celestial Weapon - Caladbolg
If you didn't already know, in order to complete any of the Celestial Weapon quests in Final Fantasy X you'll have to first obtain the Celestial Mirror. Tidus' Celestial Weapon the Caladbolg is one of the easier ones to obtain since it only has one really tough part, the chocobo racing.
In order to create Tidus' Ultimate Weapon you'll need to acquire the Celestial Mirrior, the unpowered up Caladbolg, Sun Crest and Sun Sigil. Both the Caladbolg and Sun Sigil are acquired through the same method, the Chocobo Training minigames in the Calm Lands. You should already have the first one done as it's required for the Celestial Mirrior.
For the Caladbolg you'll have to clear each of the different challenges the Chocobo Trainer sets forth for you. This includes the Wobbly Chocobo, Dodge Chocobo, Hyper Dodge Chocobo and finally the most important one, Catcher Chocobo. When you complete the Catcher Chocobo challenge the first time you'll be able to obtain the Caladbolg.
In the northwestern part of the Calm Lands you'll find a path that goes down to a ledge on the cusp of the cliff. If you're having a hard time finding this location take a look at where I am standing in my screenshot below. There's usually a man blocking this path that refuses to let you past until you complete the Catch Chocobo challenge.
Once you complete the Catcher Chocobo challenge he won't be standing here anymore and you'll be able to follow the path down to the ledge and use the Celestial Mirror at the glyph on the wall. This will reward you with the unrefined Caladbolg sword.
There's one bug or issue with this part that's worth mentioning. If you've complete the Catcher Chocobo challenge and the man is still standing on the slope and not letting you pass the issue is you can't leave the Calm Lands after you complete the Chocobo Catcher challenge and before you acquire the Caladbolg. For some reason this guy reappears here if you do.
The solution to the issue is simple, just successfully clear the Chocobo Catcher challenge again and don't leave the area this time. Instead, go pick up your sword.
You may already have acquired the Sun Crest on your playthrough of the game. Before you go wasting your time searching for it check your Key Items and see if you have it. If you do, skip this part.
If you don't have the Sun Crest you'll want to head to Zanarkand Ruins and up to the same room that you defeated Lady Yunalesca in. Located in the back of the room by the stairwell that leads downward you'll find a treasure chest that blends in with the fauna that's in the area. Inside this chest will be the Sun Crest.
If this chest isn't here, some places on the internet say you have to go down the stairs first (which will port you to another location in the room) and that'll cause the chest to appear.
Acquiring the Sun Sigil is hands down the hardest part of doing this Ultimate Weapon. In order to get this item you'll need to complete all of the Chocobo Trainer's challenges and... you'll have to finish the Chocobo Catcher challenge with a time of 0:0:0. If you don't have save states this challenge is going to be a real pain in the arse.
To get started you'll have to grab at least 12 balloons and let no more than a single bird hit you. I've tested it and can confirm that if 1 bird hits you, you can still win.
There's 2 locations that you can use save states at, the first time the camera changes angle is at the bottom of the ramp you start off on. The second area is towards the end of the course by where the Monster Arena is and a large crevase. You'll know both of these areas by heart after enough attempts because they are where the camera readjusts its position.
If you aren't using save states or you just want advice anyway.... Here's what I learned:
1. You'll want to perform sharp turns to avoid the birds.
2. Don't get frustrated and quit immediately when you perform poorly. Learning the course is very important - complete it each time even if you messed up BAD. It'll help you learn where the birds are and when to dodge them.
3. Use the D-pad instead of the Control Stick. This will give you more control of the Chocobo.
That's all there is to it really. If you don't have save states this will probably take you a couple of hours to do and it won't be the last really annoying task in this game either!