Junker, or the "Super Ultra Great Mega Trashy Monster Junker Bot" as Midbus calls it, is a trash can-like robot boss that appears in Mario & Luigi: Bowser's Inside Story and its remake, Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
As Mario, Luigi and Starlow look for a way inside Peach's Castle, they find an area of the garden filled with nothing but trash. Soon after, Midbus appears, claiming they will go no further. As Starlow dares him to fight the group, Midbus refuses, saying that the Dark Star will awaken soon. He then pulls out a remote control and uses it to activate Junker, which springs to life from the garbage nearby. Midbus commands Junker to attack the Mario Bros. and Starlow, but it simply stands idle for a few seconds before stopping and closing its eyes, then dancing when Midbus tried to control it again. This enrages Midbus into smashing the remote, which causes it to go haywire and finally attack Mario and Luigi on its own. and allows it to fight the Mario Bros. on its own.
After being defeated, Junker begins to malfunction again and rampages through the trash, finding and throwing the safe Bowser was captured in (which destroys it and frees him. It then runs though a pile of trash and further offscreen, eventually destroying itself. This opens the path to a shortcut through the garden and a pipe connected to the Pipe Yard, allowing the brothers to re-enter Bowser's body.
A stronger version of Junker, known as Junker X, can be fought in The Gauntlet.
Battle
Before each of Junker's turns, some Junker Cans will enter the battle behind it; Junker uses these cans in many of his attacks, and they are automatically defeated once the boss is taken out. Like most bosses in the remake, Junker gains the Fury status after losing half its HP, and begins attacking multiple times per turn.
One of Junker's attacks has him throw a bucket over either Mario's or Luigi's head (in a reference to the Super Famicom game Mario & Wario); they begin to blindly walk left and right while Junker pulls out Thwomps and throws them over the impaired brother. Pressing Mario or Luigi's corresponding button while they walk causes them to jump in place, and must be used to prevent them walking under the Thwomps as they try to land on them. the attack will continue until either the target brother is hit (which may render them dizzy) or Junker stop throwing Thwomps and the bucket falls off.
Junker can also walk towards Mario or Luigi and throw a ball of metal scrap at them; if they brother dodges by jumping, they will land on top of the scrap ball as Junker throws a larger one at them. If this one is dodged as well, Junker will prepare to ram through the scrap ball; Mario or Luigi must jump a third time to avoid being knocked off the ball of scrap and taking significant damage.
Junker will sometimes pick up one of the Junker Can and empty its contents; this includes enemies that will target Mario or Luigi. Junker will look at the target brother before shaking out each item.
- Cheep Cheeps bounce over their target, damaging Mario or Luigi if they jump into it. The remake replaces these with Poison Mushrooms, which can additionally poison them if hit.
- Bob-ombs light their fuses before charging one of the Bros., dealing significant damage on contact.
- Scutlets drop out and immediately charge Mario or Luigi; they are absent in the remake.
- Wads of paper and briefs will also fall out, which do nothing.
Once emptied, the Junker Can is removed from battle; in the original, Junker will simply toss it away, while in the remake the the empty can is thrown at Mario or Luigi.
Junker can also incapacitate Luigi by tossing him into one of the Junker Cans. In the original version, this attack cannot be avoided; in the remake, Junker will use a suction attack that Luigi can escape by pressing 
repeatedly. If captured, Junker will toss Luigi behind him and he will land in the Junker Can, or hit the rim and simply return to his original position. While Luigi is trapped, Mario cannot use Bros. Attacks or multi-targeting items, and if he is defeated, the can then drains Luigi's HP to 0 and KOs him as well, resulting in a Game Over. Defeating the Junker Can holding Luigi will free him; after enough turns, Luigi may escape on his own. The Junker Cans occasionally shuffle their contents between each other, and Luigi sometimes peeks out of his can and waves at Mario.
Statistics
| Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey enemy | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Junker | ||||||||||
|
HP | 1680 | POW | 132 | DEF | 118 | SPEED | 48 | Experience | 6000 |
| Fire | Normal | Jump | Normal | Hammer | Normal | Battled by | Mario & Luigi | Coins | 900 | |
| Burn | Immune | Dizzy | Immune | Stat down | 1x | Speed down | 1x | Item drop | None - 0% Special Gloves - 100% | |
| Level 24 | Location(s) | Peach's Castle Garden | ||||||||
| Mario & Luigi: Bowser's Inside Story enemy | ||||||||
|---|---|---|---|---|---|---|---|---|
| Junker | ||||||||
|
HP | 1,445 (2,168) | POW | 120 (300) | DEF | 89 (134) | SPEED | 48 (72) |
| Coins | 900 (1,350) | Level | 26 | Fire | Normal | Burn? | Immune | |
| Role | Boss | Battled by | Mario and Luigi | Location(s) | Peach's Castle Garden | Dizzy? | Immune | |
| Stat down? | Normal | KO? | Immune | Experience | 6,000 | Item drop | Max Nut - 50.0% Special Gloves - 50.0% | |
| Notice: The second set of numbers next to the enemy's HP, POW, DEF, SPEED and Coins are stat increases from the Challenge Medal accessory; a 50% increase for HP, DEF, SPEED and Coins earned, and a 150% increase for POW. | ||||||||
Names in other languages
| Language | Name | Meaning | Notes |
|---|---|---|---|
| Japanese | ガラクタモンスター[?] Garakuta Monsutā |
Garbage Monster | |
| German | Schrottbot[?] | Junkbot | |
| Italian | Bidomatic[?] | Pun on Bidone (Bin) and Automatic | |
| Spanish (NOA) | Hojalatoso[?] | Pun on Hojalata (Tinplate). | |
| Spanish (NOE) | Basuronstruo[?] | Pun on Basura (Garbage) and Monstruo (Monster). Midbus calls him "Granultramegabasurillarobot" (Big ultra mega garbage robot). May also be a reference to the Refrestruo. |
Trivia
- The Krubbish enemies from Mario & Luigi: Dream Team have a similar appearance to Junker.