After you have compleated the raven test, intentionally lose the first mission and die with 50,000 credits to activate the 'Plus' cheats. The game will restart from the first level with all items gained in the previous game, although your plot name will vanish from the 'Pilot Name' slot. The more times you do this, the more cheats you will unlock; which include better radar equipment, numerous projectiles and super-fast cooling devices.
Overweight Acs
Successfully complete the game in mission mode and wait for the credits to roll. you will now be able to play the game again with no weight restrictions on your AC.
Extra Arena battles
If you occasionally check the lower rankings of the arena, eventually three new ACs will join the fray, which are...
Rank #51: Chris Miura (AC-Vex)
Rank #52: Co-op (AC-Millionaire)
Rank #53: Lost Lamb (AC-Stray Sheep)
Extra tough Arena Battles
If you actually manage to achieve the fabled rank of nine breaker and complete the game, several new combatants will enter the arena. they're no pushover, mind!
Rank #54: Scarlet (AC-Wild Honey)
Rank #55: The Veteran (AC-New Dawn)
Rank #56: Falcon VIII (AC-MK VIII)
Rank #57: Riot (AC-Gallows Bird)
Rank #58: Matthias (AC-Funeral Mask)