Prescott's Arena is where the Prescott Mech battle takes place. Depending on what route you took in the Floatyard, you will either end up inside the Mech, or on the outside. You are always able to travel back to the outside of the area, but not to the Mech itself.
On your first visit to the area, you will find yourself in an arena surrounded by Float parts, with a cannon in its center that resembles Mickey's appearance in Steamboat Willie. After Gremlin Prescott briefly confronts you, the battle begins. You are given two options: filling the cannon's tanks with Paint or Thinner. Upon successfully completing either you are transported outside into the actual arena, where it is revealed that you faced the cannon inside a huge Mech, and as Prescott appears the true fight begins.
Depending on how you dealt with the Mech's cannon, the requirements to defeat this boss will be, ultimately, different. If you filled the cannon's tanks with Paint, you must guide the junk that the Mech throws at you to the broken panels around the arena, where breaking them open reveals gears that must be painted in, as well as control pads that must be powered up by Oswald's Remote. Restoring all of the gears will cause the two metal doors at either side of the Mech to come down on top of it.
If you filled the cannon's tanks with Thinner, or took the lower Projector in the Floatyard, you must instead erase the Mech's Toon shell and reflect it's fireballs back at it. Successfully hitting the Mech three times will cause it to malfunction and explode, shooting Prescott out into the arena.
After defeating Prescott in his arena, it'll cause a string of events leading to the final boss battle.
Though there is no need to go back the arena, you can visit it at any time. On your second visit, you will be faced with Sweepers and a Slobber. You can never return to the inside part of the Mech. Also in the second visit, the player can take a secret projector leading to the Gag Factory (possibly how Prescott transported himself between his arena and Ostown). Behind the Gag Factory, there is a thinned chest containing a gold generic Pin.
- The main storyline quests do not require you to return to the arena, but if you are on the Playstation 3 or Xbox 360 and are trying to get Thinderella, Prince Charming, or Rogues Gallery Trophies/Achievements, this is a very good place to get them.