Final Fantasy X Cheats

Get Tidus's Overdrives Fast
Here's a quick way to get Tidus's overdrives later in the game, especially Blitz Ace:

Set his Overdrive mode to "Slayer," which is attainable after Tidus has actually KILLED a large number of fiends.

Go to an area with easily defeatable enemies; and just attack with all 3 characters. Each time Tidus kills one he refills 1/5 of his Overdrive bar. If you're trying to get Blitz Ace this works well because Energy Rain attacks everyone in the group. When Tidus's Overdrive bar is full, wait until the next battle and use Energy Rain at the beginning...he'll kill all 3 and refill 3/5 of the bar. The next battle should get you either 1 or 2 kills, filling it again. After 50 successful Energy Rains, you get Blitz Ace. By this method you can do it in a couple of hours easily.

Try speeding up the process by skipping the other 2 party members' turns or getting them to do non-damage actions.