*cue Duke Nukem slogan*

They came to kick ass and chew rare candies, and I'm all out of rare candies.

NekoKnight36 said:
They came to kick ass and chew rare candies, and I'm all out of rare candies.

But they're already level 100

Hail to the King(s), baby.

Brilliant.

To get this Slowking, you must trade a Slowpoke with a Kingdra, Nidoking, Kingler, Seaking and Slaking first.

Then only you make it hold a King's Rock and trade it with a LV 255 MissingNo.

And four of them are water-types

Magikarp fits here if you go by its Japanese name, Koiking.