Here is the full list of all 18 Grapples Galore achievements.
You killed 2 or more players with 1 RPG.
Get a bounty
Hit multiple players with one burst
You got 10 kills total.
You won 1 game.
Grapple onto another player
Claim a bounty
You got your first kill.
You got 100 kills total.
You won 10 games.
Win an FFA game with only assists
You won 100 games.
You got 3 kills with only 1 shotgun.
Kill 10 players without dying
Get a kill with every weapon in one game
Hit every shot with a minigun
Kill someone 200+ meters away with a crossbow
Explode a teammate with a barrel in TDM