Can someone help me with this type of Anti cheat?

I know you can do a Hack check with game.DescendantAdded, and so far I got this:

wait(4.5) -- i am waiting so the game loads
game.DescendantAdded:Connect(function()
	game.Players.LocalPlayer:Kick("hacking.")
end

But can still get false kicks.

Every time a player joins, their character is added which could kick everyone?

Yes, I am trying to prevent exploiters from adding ScreenGUIs (Hack menus) to CoreGui.