For some reason the Nightmare version of Balloon Boy looked more like JJ to me.

1) Their hats: The hat on Nightmare BB resembles both JJ's and BB's. It uses BB's red stripes and JJ's purple stripes. The propeller (thingy) is BB's dark blue pant color and the round thing that holds them together is yellow like JJ's.

2) The shirt: Same goes for the colors of Nightmare BB's shirt/hat - red and purple stripes. The buttons seem to be dark blue (like BB's pants).

It seems that both are a combination...
Nightmare BB/JJ