I'm going to get with my ex's rival
Well, if you're single. Why not go on with it?
It would get my ex jealous and would be more likely to fall back for me.
Using someone to get your ex back is toxic. Why go through all that just to have that person back. Just move on and find someone better and let your ex be.
No I have a plan. I will make little quips about how I'm better and he will get back to me.
Those plans will never work. Emotions are hard to predict and it will cause more hurt for the both of you.