It is in the Finishing category of badges. To unlock Slithery Finisher on next-gen, you'll need the following attributes: Bronze: 61 Driving Layup or Driving Dunk. Silver: 74 Driving Layup or 73 Driving Dunk.
How good is slithery finisher?
Slithery Finisher: Improves a player's ability to avoid contact when attacking the rim. Increases a player's ability to slide through traffic and avoid contact during gathers and finishes at the rim.
Does slithery finisher help contact dunks?
Rise Up: Increases the chances of dunking in the paint. Necessary for slashing builds and helpful for other builds as well. Slithery Finisher: Another top-notch badge that allows you to finish around your defender. ... Activates multitudes of contact dunks and overall helps you become a highly effective slasher.