ALL CREDIT GOES TO JOESEFF!!
This datapack was made because the original Lucario Overhaul never got updated to Cobblemon 1.7; Cobbleverse was able to add 1.7 support.
Why didn't this datapack? I didn't like any of the answers I could have gotten.
So, I decided to solve that problem. All (except Mega Lucario) of the cosmetic items that were from the original datapack/resourcepack made it into this modpack.
Why didn't you add Mega Lucario? Because Mega Showdown already added Mega Lucario, and on top of that, Nava's Z-A Megas implemented Mega Lucario Z...which I think is really cool
Place this zip file in both your resourcepack folder and your datapack folder, and it should work!
In game: Shift + Right Click in front of your Lucario with a compatible cosmetic item, go to the upper right hand side ("Change cosmetic item" or similar), and click on that item. Your Lucario should now have changed appearance!