Get Magus Sisters
Capture all the required fiends on Mt. Gagazet then return to the monster arena owner in the Calm Lands. As a reward, the arena owner gives you the BLOSSOM CROWN. You must also possess all of the other aeons, including Yojimbo and Anima.
Next, go to Remiem Temple in the Calm Lands. After you defeat Spathi, Belgemine will give you the FLOWER SCEPTER. After defeating all the aeons at Remeim Temple, use the Blossom Crown and Flower Scepter on the door in the back to unseal it and acquire the Magus Sisters.

Get Yojimbo
Go to the cavern of the stolen faith and you will encounter a dead summoner who calls Yojimbo. Beat him and continue on to the teleport pad. Choose to travel to the chamber of Fyth and Yojimbo will ask you why you seek his services. You must answer, "To defeat the most powerful of enemies."
Yojimbo will then ask 250,000 gil for his services. Offer him half of that amount but add one gil more. So if he asks 250,000 offer 125,001 instead. Then do the same until he asks 205,000. When he asks 205,000 offer 200,000 and he will most likely accept the offer. You can offer the full 205,000 gil to hire him for sure, but if you don't mind losing an extra 5,000 gil.

Win The Blitz Ball Tournament For Prize
If you win the first tournament at Luca, you will get a trophy and a weapon for Wakka. If you lose, the game will continue but only have the trophy.

Cactuar Locations
There are total 9 Cactuar that can be found all around the world. The location of the Cactuar are:

Oasis:
Near the first Save point

Sanubia Desert (East):
In the alcove to the east, north of the tent with the save point

Sanubia Desert (West):
Search the sign near the Cactuar rock that says “20% off”

Sanubia Desert (Central):
Near the ruins to the west, look for two Cactuars running around the desert.

Sanubia Desert (East):
Near the save point under the tent.

Sanubia Desert (West):
Trapped in the treasure chest in the far west.

Sanubia Desert (Central):
Inside one of the sand whirlpools. You must exit and re-enter the area.

Oasis:
Teleport back to the airship and go on the outside deck.

Sanubia Desert:
Return to the Cactuar statue and the last one automatically appears behind you.


Al Bhed Primers
There are total 26 Al Bhed Primer. This book contain a complete alphabetical words in Al Bhed translate into an alphabetical words. So if you can complete all 26 Al Bhed Primer you can understand what the Al Bhed tribe said to you. The Al Bhed word is highlight in red instead of blue.

Defeated the last Boss (Sin)
The last boss in this game is very weird one. The size is so small, but the power is so cool. When the battle begin, cast 'Reflect' magic on it, because it will use 'Full-Cure' on it after each attack which cure 9'999 HP. When you reach Yuna's turn, cast 'Reflect' on all party members too. Use Tidus and Auron to attack and use Yuna's 'Holy' to attack it.

Secret Locations
There are a number of secret locations in FFX that you can access by searching the world map with your airship, or by simply entering passwords.

Airship Coordinates
Use the following coordinates on the airship world map, then press X when you've found the spot. These coordinates are approximates, so move the cursor around a little and press X repeatedly to find the hidden areas.

Baaj Temple -- X:14 Y:60 (find Lulu's Onion Knight and Anima here)
Sanubia Desert: X:15 Y:41 (find Tidus's Ascalon)
Omega Ruins: X:74 Y:36 (battle Ultima Weapon, steal items, and find spheres)
Besaid Falls: X:31 Y:73 (find Kihmari's Dragoon Lance)
Mi-I'hen Ruins: X:34 Y:58 (find Rikku's Sonar here)
Battle Site: X:42 Y:57 (find Lulu's Phantom Bangle here)

Airship Passwords
You can also input passwords to uncover secret locations. These passwords are hidden throughout the game in Al Bhed -- but if you can't read it, here they are (note that they have to be entered in all caps):

GODHAND -- Let's you go to lower Mushroom Rock Road where you will find Rikku's legendary weapon.
VICTORIOUS -- Enter this to access a secret area in the ruins of Besaid. Climb the tree to get your hands on Rikku's powerful Victorious armor.
MURASAME -- Another secret area in the ruins of Besaid. You will find Auron's Murasame (ability: One MP Cost) here.


Free Chocobo Rides
Go to the Calm Lands and become a chocobo trainer by talking to the female chocobo rider (leave the area and come back in on foot if she's not there). Complete the Wobbly Chocobo training exercise (cross the finish line with 12.8 seconds or less) and you will be able to ride a chocobo for free in the Calm Lands by talking to a trainer.


Overdrives:

Tidus
Tidus learns new Overdrive techniques simply by using his old ones. You have to successfully pull off an Overdrive for it to count.

Spiral Cut (available from start)
Slice & Dice (perform 10 Overdrives)
Energy Rain (perform 30 Overdrives)
Blitz Ace (perform 80 Overdrives)

Yuna
Yuna's Overdrive lets her summon an aeon with its Overdrive gauge completely filled. She is not able to learn specific techniques like the other characters.

Auron
Collect the Jecht, Auron, and Braska spheres that are hidden throughout Spira to teach Auron new techniques.

Dragon Fang (available from start)
Shooting Star (find one sphere)
Banishing Blade (find three spheres)
Tornado (find all 10 spheres)

Locations:
Jecht Sphere: Macalania Forest (after Spherimorph fight)
Jecht Sphere: Besaid Village (next to temple)
Jecht Sphere: S.S. Liki (on the bridge in Besaid)
Jecht Sphere: Luca Stadium (basement level A)
Jecht Sphere: Mi-ihen Highroad (southern Old Road)
Auron's Sphere: Mushroom Rock Road (cliff)
Jecht Sphere: Moonflow (South Wharf)
Jecht Sphere: Thunder Plains (southern part)
Jecht Sphere: Macalania Woods (southern area)
Braska's Sphere: Mt. Gagazet (Mountain Trail)

Kihmari
Kihmari can learn new techniques from his enemies by using the Lancet ability. Try this move on every fiend you meet (or switch Kihmari in whenever one of the following attacks is used on you) to build up his repertoire of Overdrives. Be sure to learn his most powerful move, Nova, from the Omega Weapon.

Jump
Fire Breath
Seed Cannon
Self-Destruct
Thrust Kick
Stone Breath
Aqua Breath
Doom
White Wind
Bad Breath
Mighty Guard
Nova

Wakka
Wakka is a Blitzball player, so it's only fitting that his new techniques are unlocked by playing Blitzball. By winning in the League and Tournaments you can expand your repertoire to the following overdrives:

Element Reels (available from start)
Attack Reels
Status Reels
Aurochs Reels

Lulu
Lulu's Fury Overdrive allows her to cast any black magic spell multiple times in a row without losing MP. Rotate the right analog stick clockwise as fast as you can to increase the number of attacks.

Rikku
Rikku's Overdrive ability allows her to mix two items together for devastating attacks or helpful potions.

Obtain Anima [Submitted by: Daniel brewer]
First get all the treasures from the temples and then go to baaj temple (which you get by searching for it on the airship at the co-ordinates X 11-16 Y -57-63) and then press X on each statue and then go to the back of the room and go through the door to talk to Seymours mother who will give you the dark Aeon Anima (hint- you have to fly back to zanarkand ruins for another puzzle and you can fly back to the other temples to enter the trials except for bevelle because you can't re-enter that trial so you only get one chance).