The FAA PTS for Airplane CPL has a matrix showing exactly what checkride tasks you will need to do for an add-on based what rating you have and what you want to add.

The biggies off the top of my head will be Chandelles, Lazy-8s, and engine out approach. But I haven't looked at that PTS in years and I know some things have changed. Correct that you can use fixed-gear since you already did the retract work for you ME.