Sneasler becomes exceptionally fast once its held item is consumed, activating Unburden, making it a formidable offensive threat. To effectively counter this, employ methods that either negate its speed advantage or reduce its offensive pressure. Utilize moves like Trick Room to reverse the speed order, allowing your slower Pokémon to act first and attack before Sneasler. Alternatively, bypass its speed entirely with strong priority moves, such as Mega Scizor's Bullet Punch, to attack and potentially knock out Sneasler before it can make a move. If direct speed counterplay isn't ideal, focus on crippling Sneasler's damage output. Reducing its Attack stat through abilities like Intimidate or inflicting a Burn status condition with a move like Will-O-Wisp severely limits its ability to deal significant physical damage.