I want to make a singleplayer game that when you join, a dummy I placed turns into the avatar who joined. How would I make it?
You can use a players UserId to do this, by using the New API
You can get the description needed by doing
local Description = game:GetService("Players"):GetHumanoidDescriptionFromUserId(userId)
Then with this you can apply the description on the dummy's humanoid by doing
Dummy.Humanoid:ApplyDescription(Description)
This should make your dummy look like the player you got got the UserId from