This article is from the Final-Fantasy and other Square Soft Games FAQ, by firstname.lastname@example.org (Nick Zitzmann) with numerous contributions by others.
The Nortune Battling Arena has some great secrets to obtain. Here's a
few of the better ones:
1. If you have the M Disc, then the battling registrar will ask you what
kind of music you wish to listen to while battling. The normal music
playing in the background of the arena also changes depending on whether
or not you have the M Disc.
2. If you have an analog controller, then put it in its analog mode. You
can now move your gear using the left joystick on your analog
3. If you put an analog controller into analog mode while playing
Special Mode 1, an option will appear which allows you to turn on
vibration. If you turn this on and you have a Dual Shock controller, you
can feel the shocks of your gear being hit.
4. It is possible to play as Elly's omnigear, Regulus (called "Regrs" in
the USA release), even if Elly isn't in the party. To do this, you need
to enter the arena after reaching the third floor of Deus during disc 2.
5. If you start a Special Mode 1 battle, open the character selection
screen, and let it sit there, you'll watch a demo of the two gears
6. Once you've finished a battle, you can use the directional buttons to
change the gear's rotation on the screen. This works for all gears
except for Siebzehn, which simply shows an unrotatable close-up of Maria
riding on the gear's back.
7. If you can select Regulus in a Special Mode 1 battle (see number 4
above), you can also enter Gear-Level-2 difficulty in a Special Mode 2
battle. This level is more difficult, but winning grants you more G and
BP than the other levels.