How to change a character when a specific player / team has joined it. Without any gui and a button?

Problem

• You are trying to set the player's character locally. This causes issues with how other players will see your character (I don't recommend using the client to set the character).

• You have a memory leak occurring due to the repeat/until loop. You shouldn't connect to an event more than you need to.

Solution

• Run the code in a server-side script to allow all players to see the new character.

• Remove the repeat/until loop to fix a memory leak.

Code

--=== Services ===--

local ReplicatedStorage = game:GetService("ReplicatedStorage")
local Players = game:GetService("Players")

--=== Variables ===--

local CreatorChar =  ReplicatedStorage:WaitForChild("Characters",10) and ReplicatedStorage.Characters:WaitForChild("CreatorFurry",10)

--=== Hooks (Connections) & Main Loop ===--

Players.PlayerAdded:Connect(function(player)
	if player.Name == "ZEWS228" then
		player.CharacterAdded:Connect(function(Character)
			if Character.Name == "CreatorFurry" then return end -- If set, don't re-set
	
			-- Set the player's character
			local oldModel = Character
			local newModel = CreatorChar:Clone()
	
			local oldCFrame = oldModel:GetPrimaryPartCFrame()
	
			player.Character = newModel
			newModel.Parent = workspace 
			newModel:SetPrimaryPartCFrame(oldCFrame)
			oldModel:Destroy()
		end)
	end
end)

Conclusion

If you have any further questions or anything in this answer was unclear, feel free to contact me via Discord (phxntxsmic#2021)