VV magnets will work on Steph, just not very well. That's why Wyrmmaster created Steffy Stax. The magnet poses will only work with the magnets they are designed for. Ordinary Vicky poses work fine with Steph, and vice versa. You might have to do some tweaking. But MOR (morph) poses can't be swapped between the two, because they have different morphs. MOR poses only work with the figure they are designed for.