It could be a clumsy way to increase spread damage. Sand Slammer, Thorn Tempest, Petal Blizzard, Glaciate, the way to reduce the effectiveness of an opponent using one of these is to be more methodical about your bench and limiting what you bench. Even Empoleon, the opponent has power over the damage it does by being more conservative about what is benched in an Empoleon deck to increase your bench. This is a way to get around them. As an attack, it is a very awkward way to do it though. Duskull only has 50 HP so it is likely to be knocked out after the attack and your opponent also gets a chance to respond to the new member of the bench.
It could also be a way to reduce the damage done by Flareon's Vengeance attack. That's -10 damage. Again though, Duskull is probably taking one for the team in trying to set the opponent back in this way.