These Duskulls have SOULS!
W's Dusk-souls adds a way to get wither skeleton skulls for those who are playing Cobblemon with no vanilla mob spawns. Find special versions of Duskull, Dusclops, and Dusknoir in Soul Sand Valleys. Duskull, Dusclops, and Dusknoir have a 1, 2.5, and 5% chance of dropping a wither skeleton skull as well as their normal loot pool on defeat.
Future updates (no promises)
This pack needs to be put in both your resource pack and data pack folders to function properly.
Since resource packs and data packs do not share pack formatting, the data pack will show up as "Made for an older version of Minecraft" - It will work fine!
Thank you to the much smarter people on the Cobblemon Discord who helped me develop this. Credits can be found in credits.txt.

Wait, these Duskulls have SOULS?