For doubles. I don't think the Pokemon that can learn this move have Unburden
I believe it does. I tried it in this replay
https://replay.pokemonshowdown.com/gen8ou-1282443802-mn22auf6uzfyi4qpejo5iqufs1uyelcpw
Both Skuntank and Slurpuff were max speed. Skuntank went first in one turn and Slurpuff went first the second