With GenX you can get many to most V4 morphs transferred the Genesis…but to transfer them, you need to have them. Which pretty much means that yes, you need at least the Morphs++ (I’m not 100% sure, but I think the basic morphs are included in the Iconic Shapes) to go along with the shapes. Of course, then you’ll need the characters on top of that…with no guarantee that the character morphs will transfer (95++% they will…but).
If you don’t already have Gen4 figures and morph packs, it’s going to be a lot more expensive to convert them to Genesis, which means you’d probably be better off sticking to Genesis content. If you have a large library of Gen4 stuff and the morph packs…it’s a fairly cheap/easy way to do it.