I changed a little thing which caused the whole thing to break, here is what is screwing it up.
for index, value in pairs(players) do
countdown = game.StarterGui.readygo -- starting countdown gui thing
readygogo = countdown:Clone() -- cloning it
wait(0.5)
readygogo.Parent = value:WaitForChild("PlayerGui") -- putting it in playergui but doesnt work
wait(0.5)
value:WaitForChild("PlayerGui").readygogo.gogo.ready.Visible = true --makes it visible but doesnt work
There are no error messages when I look in the output, yet it still doesn't work. Help? :v

2 comments
Try changing the WaitForChild to FineFirstChild on line 5. :)
FindFirstChild* - Fail