Just use a save game from Armored Core 2 to load your game
Hold: R2, L1, Start then all directions, select X, Circle.
Rank 1ST in THE ARENA!!!!!
Ok all the other people that said some ways of beating the arena, well i cant really explain, not to brag but that 2nd place prisoner guy in 2nd place only took me 2 tries, but Ares is hard for head-head. To beet him, all u have to do is pick a nice fast strong quick overheating weapon, ~~AVOID HIS MOONLIGHT ARM MOUNTED LASER BLADE!~~ and get on something like a high hill to beet him.
OPTIONAL: just go to the place, the etal base like that other "submitter" that said something about the multiple warhead missile, go on the pipe (and no i did not copy you) or stay on the plat form, use the tank legs and equipped 2 of those big rocket launchers that cost about 19000Credits for a back part (the one that cost the most and just lock on to areas and fire your missiles, u should have 8 shots total. if he still survives, make sure your arms are the dual grenade or bazooka arms
Double Sword Damage Trick
Get the "shoot disk out of sword" ability and walk up to someone very close and hit them with a disk. it should do more damage as both disk and sword are hitting.
Most people just make their robots with the most heaviest and most armored stuff and think it will be the best. not true. i used to make mine like that, so i tried something different and equipped the most lightest and smallest arms and legs, best lightweight core and average head, that 1000 ammo machine gun and this laser blade thingy. my ac had good mobility and speed and u can easily move behind your opponent and defeat him.
Arena Battle Hint!!!!
First you buy the part that fires multiple warhead missile, then if your far enough in the game, buy the back part that adds 10 percent of ammoto all parts. Then go to the level were you are were the spaceship crashed. Fly to the top of the ship and keep a lock on your opponent and fire a rain of missiles on your foe! (hint:for more damage, get the extensioin part that fires extra missiles to do more damage.) I got to rank 1 this way!
First Press L2 + R2 + R3. Now a "Limiter Release" system error message will appear, and you will have unlimited energy during this time. After approximately one minute, the "OB Down" message will appear. It will last almost as long as the previous error depending on the core, but you will not have any energy. After "OB Down" is completed, your AC will recharge and return to normal. Make sure you finish off your enemy before you become vulnerable.
Secret Part: Scope Eye
In the Scissors Forest Mission Escort AC Parts Transport, blow up the vehicle you are supposed to protect and you will find an AC head where the vehicle exploded, quickly pick it up because the mission will end shortly after you blow it up. This is an enhanced version of Night Eye and it's the same head the grey AC in the beginning cinema uses!
Simply beat the game then your ac can go overweight. Also once you beat the game there will be a new place that has 3 HARD!!!! missions. once you beat them 3 you get 2 new parts. The INSIDE part orbit maker, and floating leges, these legs are the fastest in the game but can only hold around 3980 lbs. but does it matter, no, because you can go overweight!