Become a Prizefighter

Become a Prizefighter is an unmarked quest in Fallout 2.

The New Reno championship is a boxing tournament that the Chosen One can join if they wish. This quest relies heavily on the Unarmed skill.

Detailed walkthrough
If the Chosen One goes into the Jungle Gym and talks to Stuart Little, they can box. If one's Strength is below 6 or is female, they will have to pass a Speech check.

Four different opponents will have to be defeated in order to win:
 * First fight: Joqq ($50, 500 XP)
 * Second fight: Pete McKneely ($50, 750 XP)
 * Third fight: Evan Holyfeld ($400, 1,000 XP)
 * Final fight: The Masticator ($1000, 2,500 XP)

The sums are given assuming that the Chosen One gets the default 50% of the winnings; with Speech 76% and Barter 76%, they can haggle for 75% instead. They would also get any corresponding kill experience if they happen to beat a boxer to death; the announcer would count this as a knockout.

The ways of winning a match include:
 * Knockout (scoring a Critical Hit that knocks the opponent unconscious, or if they get a critical failure that would make them lose their next turn),
 * Technical knockout (making them flee), and
 * Points (somehow managing to make a fight last 12 full rounds and win the majority of them by landing more punches than the opponent).

Upon winning all four matches, the Chosen One is awarded the Prizefighter reputation title, which also allows them to loot the gym lockers without the inhabitants stopping them.

If the Chosen One loses a fight, they must ask Little for a rematch immediately, or they won't get another chance, and pass a Speech check. The royalties will then be dropped to 25% but the XP gained is the same.

A low Intelligence character can box, too, provided they are male and have a Strength of 6. Apart from getting no pay and rematches, there are no differences to how the quest functions.

Fighting
When a fight starts, the Chosen One is equipped with boxing gloves. If they have plated boxing gloves, these will be used instead.

In a fight, only punching the opponent with the gloves is allowed; any other attack would get the character disqualified. Unlike real-life boxing though, it's permitted to hit any part of the body and finish off a fallen opponent.

The Masticator can bite off the Chosen One's ear - reducing Charisma by 1 and adds the ear in the inventory. If the Chosen One has an Unarmed skill at about 160% or higher, they may end up biting off the Masticator's ear.

Boxers comparison table
Remarkably, the second opponent Pete McKneely is weaker than the first, Joqq.

Alternate boxers
If the boxer that the Chosen One is meant to face is dead, an alternate one is substituted. The substitutes are: The first and the last replacements cannot actually be fought. Joqq isn't present anywhere before the fight (thus cannot be killed), nor is there a code entry for replacing him. If the Masticator is killed in the Shark Club, there's dedicated code that makes Stuart Little disappear upon returning to the 2nd street map unless the player already completed the quest, making it impossible to proceed.
 * Joqq — Mal Fisto
 * Pete McKneely — Tony Gunn
 * Evan Holyfeld — "Steel" Mark Torrance
 * Masticator — Xander "the Sure Thing" Holyland

An alternate opponent is also substituted for the rematch is you've lost a fight. Whether this is an unfinished/dropped feature or a bug is anyone's guess. Most probably, both (see bugs).

The rewards for defeating the backup opponents are the same as for the normal ones.

All of the alternate boxers use generic boxer models that have the same stats as Joqq:

Behind the scenes

 * Among the nicknames to choose for the boxing ring, the Chosen One can pick Balboa, Clubber Lang, Drago or Apollo — references to the movie series Rocky.
 * One of the other possible names is Glass Joe, a reference to the NES game Punch-Out!!.
 * Masticator biting off the Chosen One's ear and vice-versa is a reference to the infamous boxing incident in which Mike Tyson bit off a portion of Evander Holyfield's ear.

Bugs

 * At the start of every match, the Chosen One gets a permanent +3 bonus to Damage Threshold for normal damage (to a maximum of 100), -1 for plasma and explosive damage, and a bonus to Damage Resistance (DR) for each listed damage type except fire (to a maximum of 90%). If they use normal gloves, they get +1% DR for all four types, and for plated ones, they get +2% for normal damage, +5% for laser damage and +1% for the others (there's also a -1% penalty to Chosen One's unlisted EMP resistance, but this doesn't matter in the least; the electricity resistance is unaffected).
 * The Chosen One gets to keep these bonuses even after losing a match. Therefore, they can deliberately throw one match and ask Stuart Little for another shot to get the fifth toughness bonus.
 * The bug's cause is the game not taking away DT/DR bonus stats from the gloves at the end of the fight.
 * If the player character has lost a match by a critical failure that caused them to lose their next turn (counted as a knockout), they will immediately lose the following match, too, as soon as it starts (by a knockout, too), thus failing the quest.
 * A workaround is to ask Stewart Little to wait, then enter combat mode (it will immediately end by itself) before the next match.
 * The reason is the same as the previous bug — fights in the ring are not terminated correctly, so the player character continues to serve their penalty at the start of the next combat.
 * An alternate boxer is also substituted for the rematch if you've lost a fight.
 * That's because when the boxer's object is destroyed after the match, the same procedure is called as if he has been killed and the script logic doesn't make a distinction.
 * This way, you can fight Xander Holyland if you've lost to Masticator. Be wary that Stuart Little will still disappear if you leave the 2nd Street map before doing the rematch. The winning message will still say that you defeated Masticator.
 * In the unpatched game, when Masticator bit off the Chosen One's ear, their Charisma wasn't decreased by one but rather increased by current Charisma minus one (due to a scripting error instigated by a counterintuitive function name).