Di Base, 888x, Northstar/Protostar, plenty of SE enabled yoyos, at least 1 FHZ, a few loopers, at least 1 Delrin, and at least 1 4A. At least 1 yoyo of each manufacturer. This, of course if for someone who has played for a few years
Gotta go with Duncans to start with. Imperial and Butterfly, you have to accept the classics. Then a FHZ.
After that, we need a pair of loopers. We should all have at least 1 off-string. We should have an all plastic wing shape, a metal and plastic wing shape(yeah, nod to YYJ there…) and a full metal wing shape. We should all have a responsive wing shape or at the very least a semi-responsive wing shape such as the Lyn Fury. If we want 3A, we should have a pair of wing shaped yoyos for this purposes. We should have one yoyo set for 5A.
The idea of having a yoyo with swappable bearings or can be converted from responsive to unresponsive is good. Very good actually.
We should have a yoyo with hubstacks, just for the option!
And lastly, we should all have a much loved beater we carry with us everywhere. Make, model, material is not important. Cost is irrelevant. All you have to do is want to keep it handy all the time. In my case, it’s the DM2.