You should be able to modify ServerScriptService.AvatarEditorServer to support R6. I think there are few parts needs editing.
Bundles: (ServerScriptService.AvatarEditorServer, line 255)
You just need to check if Humanoid.RigType is R6 or R15. I think you can just parent the bundle’s children to the character.
Scaling:(ServerScriptService.AvatarEditorServer, line 323)
You need to check if the Humanoid.RigType if R6 or R15. R6 does not support scaling.
I think that is it to support R6. Further testing might need to be done.
Probably.
For custom characters, you probably need to change humanoid:AddAccessory() to your custom method of attaching accessories to your character; Welds or whatever.
For custom accessories, you need to upload the accessory as a model and add the Id and Name to the respective category in ReplicatedStorage.Catalog.Accessories.CATEGORY
is there any ways that can get all the items from roblox catalog, and load it back into the game instead of getting id of each items and put into modules
I should have thought about saving when making this. I think you can use a BindableFunction to get what the player is currently wearing from playerWearingAssets table in AvaterEditorServer and save that table to a data store. As for loading it, I should have made the avatar editor more modular. Right now there is no way to apply all the accessories at once. You can probably use a BindableEvent and call the wear(player, id) function for all the assets.
There are two ModuleScripts in ServerScriptService that can update the catalog database. You just need a proxy. There is more information on this post:
but for custom accessories, do I have to make a model of the accessorie, or the handle of the accessorie, I have been trying and I dont seem to make it work, is there something that Im doing wrong?
Seems to be working for me in R6, all I had to do was add this to the script (or make another serverscript), and put this in it, definitely a bad solution but hey, it works… kinda. (set your game settings to R6 only or this will break literally everything, also packages literally do not work)
game.Players.PlayerAdded:Connect(function(plr)
plr.CharacterAdded:Connect(function(char)
char.Humanoid.Changed:Connect(function(thing)
if thing == "HipHeight" then
char.Humanoid.HipHeight = 0
end
end)
end)
end)
Why can’t this be R6 as well 
