Arena Trap Duggy in GSC would be fantastic. However, it wouldn't be good for trapping Jolteon since they always BP anyway.
As of now the best thing Duggy has going for it in GSC is Screech. With that Speed and STAB EQ it might be able to do something with Spikes down. But not really. It's way too frail and is pretty weak, even after a Screech.