Luigi is first found in the jungles of the Ancient Gardens, where he and Spawny accidentally wake up a Piranha Plant with a Rabbid on it, scaring Luigi away while also causing Spawny to get scared and fuse the two together, creating the Pirabbid Plant. Luigi will be unlocked as a playable hero after the battle with the Pirabbid Plant.
In-game, he is described as a Scout, having the best movement capabilities of any hero in the game as well as good offense, however has very bad defense as Luigi has the lowest HP of any hero in the game by far. Because of this, Luigi is best suited at the back lines of battle hitting enemies at very long range like a sniper. His primary weapon is Precision, having very large damage at long range, and his secondary weapon is a Sentry, allowing Luigi to send an explosive sentry into the heat of battle while Luigi stays at the back lines.
Unlike other heroes, Luigi also has the ability to Team Jump twice with two heroes in a row, increasing his movement capabilities by far. His special abilities include Steely Stare, allowing Luigi to attack an enemy who moves during their turn or on account of a forced-movement ability if they are in Luigi's range, and Itchy Feet, which increases the maximum movement range of all heroes in his range, including himself. His Steely Stare can also be used with forced movement abilities( e.g. Rabbid Yoshi's Scaredy Rabbid ability) and/or his brother's M-Power ability to deal extra damage and lure enemies out of cover(especially if Luigi is on higher ground) and his Steely Stare can also be used with weapons that have a high chance of inflicting Burn, Push, or Bounce because they can also force enemies to move.
- The first Precision weapon Luigi has is called the Suction Destruction, which is modeled after the Poltergust 5000.
- Another one of them is called the HMS Let's-A-Go, which is a reference to the signature catchphrase of Mario and Luigi.
- While using the Sentry without cover, Luigi will do the infamous "Dab" after launching the Sentry.