Easily Beat Jecht
GET AURON'S CELESTIAL WEAPON ( Suggested )
First before fighting him, I would suggest getting Auron's Celestial Weapon. First, go to the Calm Lands and go to the place where you faught the big Defender X dude. You will see thst part of the map fades, go to that spot. If you haven't been here yet, you might want to go into the cave to get a new Aeon Yojimbo. Go to the left outside the cave until you find a sword. Click X on it and you will have the Rusty Sword. Next, you have to catch all Fiends from 10 different places and you will get a Mars Crest or Mars Sigil.
Then go to the Mi'Hen Highroad and get on a Chocobo. When you see the gate that leads to to Mushroom Rock Road, go to the side of where you just came out of. You should now be in the Mi'Hen Oldroad. Go to the very end and you should get the Mars Crest/Sigil. Now go to Mushroom Rock Road and follow the path. Turn on your second right and there should be a glyph looking thing. Press X on it and you should go up. Press X around the statue somewhere and there will be a cut-scene. You now have Auron's Masamune. Now go to Lake Macalania and look for the shiny road in the forest. Go up until you run into a fork. Take the one to the left and talk to the ball and present Auron's weapon TWICE. The Masamune now has the abilities Break Damage Limit, First Strike, Triple Overdrive, and something else. Now find a Save Sphere and return to Sin. Go to where you are about to enter the tower. Make sure your guys are strong.
When the battle begins, have out Tidus, Auron, and Kimahri. When it is Tidus' turn, use Hastega. Now keep attacking him and he will die. On his Second form, use overdrives and have Rikku come out and use one of the Stamina Tonics you got for getting all creatures in some place. The battle will be over in no time.
Added by: 1122andyozz33 May 7th 2009, ID#31930