Win the Arena Battle is a mission in Going Commando, taking place at the Maktar Resort, Maktar Nebula. After Abercrombie Fizzwidget told Ratchet that the Unknown Thief had been seen on the Maktar Resort, he showed Ratchet a commercial for the broadcasting of the Galactic Gladiators event taking place in the arena on the resort. Intrigued, Ratchet visited, believing the gladiators did not appear too challenging. After winning the battle, Ratchet won the Electrolyzer.
"Win the Arena Battle" is one of two missions available upon reaching the Maktar Resort, along with "Find a way to the Thugs-4-Less Jamming Array". During this mission, it is possible to earn the skill point "Clank needs a new pair of shoes", and one platinum bolt can be found along the path.
A nearby ramp leads down to a larger platform, where a Thugs-4-Less Brute will appear from behind of a stack of crates. These thugs can deploy a set of Megacorp Chickenbots and also have a ranged attack, but are a viable target for any available weapon .Take the left path for this mission, or the right path for "Find a way to the Thugs-4-Less Jamming Array". In the Megacorp vendor, no new weapons are available, and you likely still can't afford the Blitz Gun (but if you have not yet purchased the Chopper, now would be a good time).
Along the left path, you will find a series of slot machines, and at the end, more Brutes and Chickenbots. Take them out first with the Chopper, and then hit each of the slot machines with your wrench. The slot machines will either reward you with ammo, bolts, nanotech, a large sum of bolts on three bar icons, nothing if they do not land on three identical icons, or explode if they land on three explosive icons. After exploding, two Chickenbots will attack. Hit all of the slot machines repeatedly until each of them explode, or until you earn the skill point, as you will earn more bolts than you lose. Furthermore, the path is littered with lights and floating billboards, which can all be destroyed for bolts. After you've finished with the slot machines, head to the elevator and go up. Destroy all the Chickenbots and Brutes here, then head inside the limo, which will take you to the next area.
Here, jump to grab on to the ledge (lit by red lights), and pull yourself across to the ladder and upwards. When you get up, a dropship will drop off several more Thugs-4-Less Brutes, on a the second platform ahead. A pair of Brutes will engage you beforehand, which must be defeated along with any deployed Chickenbots. The Gravity Bomb is viable here due to large number of enemies. After these are dispatched, the Brutes spawned by the dropship must be engaged on the next platform, which is best done by staying at a distance and using a weapon (both the Gravity Bomb and Chopper are good) while strafing to just wipe them out before even crossing the gap, dodging the incoming fire. On the right platform with a crane, you can jump up to grab a platinum bolt before continuing. At the end of the path, use a wall jump to head up, by jumping to the wall on one side and bouncing across to the next, repeated until you reach the top. Head inside the building here, and use the Chopper to wipe out the enemies, several more slot machines can also be found here.
After this, a walkway is the only thing between you and the arena entrance. Defeat the Chickenbots, and then another Megacorp dropship will arrive. Defeat all of the Brutes, refill your ammo at the Megacorp vendor, and then head into the arena. A cutscene will commence, and you will begin the "Battle for the Electrolyzer" challenge.
Battle for the Electrolyzer
After this, you will earn the Electrolyzer. It would be wise to continue completing as many arena battles as you can to earn bolts, which will be useful later on. The arena is also a good way to upgrade your weapons. Complete more challenges (see here for a guide) until you find them too difficult, at which point, leave the arena, and the short mission "Repair the energy bridges" will commence.