I'm really bad at Jigglypuff dittos

PrinceOfKoopas (Leaf's hat Jigglypuff, player 1) versus Jekly (straw-hat Jigglypuff, player 2) in a 1-on-1 Tourney.
For some reason, I'm really bad at playing against other Jigglypuff, especially with my own Jigglypuff. I don't know how to improve this.