Get Ultimate Weapon for Tidus
To get the Caladbolg, you need to have the celestial mirror. Once you have it, go race with the chocobo trainer in the Calm Lands. If you win the race, the person blocking the path in the north part of the Calm Lands will be gone. Then you can use the celstial mirror to get the Caladbolg.

Hidden Locations
After u can control the airship go to the search option on it and type in the following:
X Coordinats/Y coordinates/Location
11-16/52-63/ Baaj Temple
12-16/41-45/ Sanubia Temple
29-32/41-45/Besiad Falls
33-36/55-60/ Mi'Ihen Ruins
39-43/56-60/ Battle Site
69-75/33-38/ Omega Ruins

Extra potions
When you are on the first boat ride with Yuna and her friends, go below deck to where the seasick person is. There is a suitcase in the room. Kick it, and it will give you one potion at a time. It will give you up to 20 potions.

Overdrives

Kimari: Use the Dragon Sword ability to drain HP and MP from the enemy. If the enemy has a Blue magic skill that Kimari can learn, he will gain it automatically. The only one that is difficult to get is "Sunshine", which you obtain from the Omega Weapon.

Auron: Find different Jeckt Spheres laying about the world. Some of these will give Auron a new Overdrive. You need to find all ten to get Auron's final overdrive.

Tidus: Just keep using them over and over. After a while, he will learn his next Overdrive.
Wakka: You can win new overdrive roulette (slots) types in the Blitzball Ranking and Tournament modes.

Lulu: Rotate the Right Analog-stick clockwise as fast as possible. The number will go up the more you rotate it. The more you level Lulu up, the easier it is to cast multiple spells.

Rikku: Rikku's overdrive combines items to create special attacks and power-ups during battle. You have to choose any two items to combine. Note: Two of the same kind will work.

Location of Crests and Sigils
To aquire unlock the potential of anyone's Legendary Weapon, you must have the Celestial Mirror and the Crest and Sigil of that weapon. For Tidus, the type of Crest and Sigil is the Sun. For Yuna, it is the Moon. For Auron, it is the Mars. For Wakka, it is the Jupiter. For Kimahri, it is the Saturn. For Lulu, it is the Venus and for Rikku, it is the Mercury.
The location of each: Sun Crest- Zanarkand Dome (Where you fought Yunalesca), Sun Sigil- Race the chocobo trainer in Calm Lands and finish with a time of 0:00, Moon Crest- Besaid Isle (Beach), Moon Sigil- Defeat every Aeon at Remiem Temple, Mars Crest- Mi'ihen Highroad(Oldroad,South), Mars Sigil- Capture 10 monsters of 10 species in 10 different regions, Jupiter Crest- Luca;inside locker in the Aurochs' locker room, Jupiter Sigil- offered as prize in blitzball league matches but only after Wakka has all of his reels, Saturn Crest- Mt. Gagazet columns after Seymour battle, Saturn Sigil- capture all blue butterflies without touching any red ones in the butterfly hunt game in Macalania Woods, Venus Crest- Farplane at Guadosalam, Venus Sigil- Evade lightning bolts on the Thunder Plains 200 consectutive times without being hit, Mercury Crest- In sand whirlpool in Sanubia Desert, Mercury Sigil- complete the Village of Cactuars mini-game and look for treasure chest in the sandstorm area.

Kimahri's Legendary Weapon
To aquire Kimahri's Legendary Weapon, Spirit Lance, you must have the Celestial Mirror and activated 3 of the Qactuar stones on the Thunder Plains. After activating 3 stones, find the small, ruined lightning tower on the right side of Thunder Plains-South. Press "SQUARE" while next to it to send a bolt of lightning to the tower, revealing a treasure chest holding the weapon.

Auron's Legendary Weapon
To aquire Auron's Legendary Weapon, Masamune, you must have the Celestial Mirror and acquire the Rusty Sword, found on the eastern cliff of the Cavern of the Stolen Fayth in the Calm Lands. Take the Rusty Sword to the statue of Lord Mi'ihen on Mushroom Rock Road. Access to this area was previously prevented by Clasko. Place the Rusty Sword before the statue to reveal a glyph. Touch the glyph to reveal the Masamune's secret location.

Lulu's Legendary Weapon
To aquire Lulu's Legendary Weapon, Onion Knight, you must have the Celestial Mirror and return to the Baaj Temple (where Tidus first woke up) and dive underwater. Swim towards the doors to the north and fight Geosgaeno. After defeating Geosgaeno, search the southern part of the circular underwater area and look for a treasure chest containing the weapon.

Yuna's Legendary Weapon
To aquire Yuna's Legendary Weapon, Nirvana, you must have the Celestial Mirror and you must capture all 9 types of fiends in the Calm Lands region. After collecting them all, return to the monster arena owner and he will produce a treasure chest containing the weapon.

Wakka's Legendary Weapon
To aquire Wakka's Legendary Weapon, World Champion, you must have the Celestial Mirror and talk to the bartender in the Luca Cafe. If she refuses to turn it over, it's because you have been neglecting to play Blitzball

Airship Passwords
Password #1- GODHAND
This is the area in which Rikku's legendary weapon is hidden
Password #2- Victorious
Opens a scret location in Besaid Ruins. Climb up the tree branch to find Rikku's Victorious, an armor that nullifies 3 types of elemental types
Password #3- Murasame
Opens another secret spot in Besaid Ruins. Cross the platform to find Auron's Murasame, which bears the 1 MP Cost ability
(Sorry, I messed up on the 1st one I sent you. Here is a part that NEEDS to be included)
Every password is case-sensitive

Game Shark Codes

Effect                                         Code

Master Code (M)                          0E3C7DF2 1645EBB3
                                                  0C08E7C3 F8A9A297

Infinite Gil                                    3C28CEF7 85F19EFF

Al Bhed Fully Translated               3C28CDBF FBFFFFFF

Super HP/MP For All Characters   3C120FFF 2FC6FEF2
                                                  3C120F3F 2FC6FEF6

Max Stats For All Characters        3C120727 A4FDFFFF
                                                  3C12073B F862CE11
                                                  3C12073F 2CBDFE0A
                                                  3C120747 2CBDFE0E