Mine was, when re-playing, discovering that after killing Spherimorph and getting the first sphere, I could make it all the way back to Besaid Island to pick up the sphere there without having to fight the bastard of a Dark Aeon. As a result pick up the rest on the way back and once reaching Gagazet pick up the final one and have all of Auron's Overdrives early in the game.

Hmm, never knew that, might try it out next time I play.

For me, jeez, a toughie, I thought you were talking about storyline situations, in that respect, it was how pretty damn obvious Auron was an unsent, including him getting very close to being sent when Yuna sends Lord Jyscal.

Also I never knew you could save EITHER Luzzu or Gatta, I thought Luzzu always died, but it depends on what choice you make in terms of Gatta fighting in the frontline or staying behind.

As soon as you get the first sphere from Spherimorph the Shoopuf taxi opens again so you can go back. It takes about an hour there and back a little less if you skip fights. Also the dialogue has changed on the NPCs to reflect all the events in the game thus far. I did it on a whim once and was like, COOL.

The Luzzu and Gatta thing I found by mistake first time it as Luzzu, second Gatta. BUT I did discover that in the official guide it tells you the wrong options to get whichever one to survive.

It's like the Sled journey to Macalania Temple, there are options to have conversations with ALL the characters I have only had Rikku and Lulu and Auron.

Yeah I knew about the conversations with the ladies situation because naturally you like to mix the options to see the results. Where as the Luzzu and Gatta situation I always decided to use the option I'd say if I were Tidus, which is for Gatta go not take part in the Operation. So I never knew about it!

That you can get Valefor's second overdrive from a dog in Besaid. Seriously, WTF?

Yeah, and there were rumours there was a second overdrive for loads of other Aeons too! :D

Yeah, and there were rumours there was a second overdrive for loads of other Aeons too! :D
Yep. You talk to the Chocobo on the Djose Highroad to get Ifrit's second overdrive. :)