Hello! Here's my idea:
While it technically doesn't have four attacking moves, I'd recommend potentially a Frisk and Trick Set. With this set, the Grimmsnarl would carry a Choice Band (or maybe Scarf if you'd like, or for if you're doing a trick room team).
The opponent's item can be seen, and then you can decide if you want to switch your Choice Band with it. Obviously, it would be best against Special Attackers, and I suppose some stallers.
Here is a moveset for it; I'll use you 252 Speed and Jolly idea you had:
Grimmsnarl @ Choice Band
Nature: Jolly (+Spe, -SpA)
EVs: 252 Spe / 252 Atk / 4 SpD
- Spirit Break / Play Rough
- Darkness Lariat / Foul Play
- Stomping Tantrum
Hello again! In the EVs section, I used 4 SpD EVs, as many current Poison and Fairy Type OU Threats are Special Attackers overall, like Clefable, Toxepex, Togekiss, Gengar, and Hattrene. There are a few physical attackers, though, so this could definitely be switched. In addition, Trick is used for the... Trick Trick, the second and third move slots are for STAB, and the last move, Stomping Tantrum, can be used to deal with Poison and Fairy Types. However, they have many other options, such as Drain Punch, Power Whip, Leech Life, Shadow Claw, and the Elemental Punches.
I hope I helped!