On the menu screen go to war zone then pick any robot. Win your first match and then it will show your next apponent then press select and the triangle. You will then be the robot that was meant to be your opponent and you will be against the last robot you beat.
More Credits
When setting up you robot, buy weapons and armor from the scrap yard, add them to your spares save and exit back to the main menu. Return to robot setup you will see the items are now full price, sell them and you should have more money than you started with.
Unlock Arenas for Use in Free Play Mode
In free play mode highlight an unlocked arena, next to a locked arena. as you press the direction towards the locked arena press x. *will only work if you move from an unlocked arena to a locked arena.
Unlock Robots
Firestorm - Unlocked By Completing: Hamburg Heavyweight (Germany)
Terrorhurtz - Unlocked By Completing: Heavy Bomber (Siberia)
Panic Attack - Unlocked By Completing: Scrapyard Challenge (Sao Paulo)
Mortis - Unlocked By Completing: Liberty Lightweight (New York)
Pussycat - Unlocked By Completing: Alpha Viking (North Sea)
Diotoir - Unlocked By Completing: Rooftop Punishment (Japan)
Thor - Unlocked By Completing: Robot Wars Championship (UK)
Chaos 2 - Unlocked By Completing: Robotwars World Championship (London)
Hypnodisc - Unlocked By Completing: Flip Frenzy (Siberia)
Behemoth - Unlocked By Completing: Russian Rampage (Siberia)
Razer - Unlocked By Completing: Nerves Of Steel (New York)