Track slow down object 2

I have a question I want to track an object in a video using mocha pro and then apply an effect that slows the object down in the video. What effect would I use, would it be a sapphire effect or an Continuum and which one.

Also, I tried using two or three of the time effects with an AE mask, did not work at all. Which effect should I use.

I can slow down the video I just want the object to slow down not the entire video. I figured I can track the object and then apply an effect.