Junker

Junker is an antagonist in Mario & Luigi: Bowser's Inside Story. It is a rumored boss battle in Super Mario 64, and is believed to be found in a small portion of personalized copies.

Junker's existence remains largely unconfirmed, only being backed up by a handful of anonymous sources and a German gaming magazine, which teased the boss fight among other boss battles.

Appearance
Junker resembles a large pink trash bin. Inside of the bin are a pair of oval-shaped eyes, similar to the ones seen on Bob-ombs. It has metal tubes as arms, and vacuum like hands. It also has brown feet, although the in-game screenshot appears to show it having yellow feet.

Reports
It is worth noting that these reports are from anonymous sources, and as such they should be taken with a grain of salt.

Report 1
"Oh man do i remember this fight. You had to get the guy to spin around over and over, and then you got on top of some sort of watch tower and throw stuff at him??? Idk, it's been a long time."

Report 2
"They brought back the trash guy from Mario 64. Why would they bring back such an obscure and honestly annoying character? Why not bring back something people recognize, and preferably a character people don't hate"

Report 3
"On the topic of most hated boss fights, does anyone remember the trash robot from Super Mario 64? It was in some sort of landfill. There wasn't any monologue or anything, just straight into the fight. You had to get him to run into the trash heap, where he would bounce off and knock over a whole lot of trash. You'd then need to drop the trash into the guy. It wasn't a three hit health system like a lot of other Mario bosses, you just kept filling him up. Eventually he'd overload and explode, dropping a star along with it. I remember he would pick me up like the guys in TTM and throw me into the trash heap. Dude took so long and he was super annoying. At least give me a health heart before starting the fight!"

Report 4
"I could have sworn there was some sort of battle with a pink bin. Pretty sure the guy was brought back for the new Mario rpg. I was pretty impressed with the detail on everything. All the trash bags were fully modelled. Granted, they were really low detail but they looked pretty good. I had no idea how my dusty Nintendo could handle all of it, plus the big trash guy and Mario at the same time."