Familienoberhauptvogel
Banned
Equipment, as a rule, can only attach to creatures you control. You could not use the Equip mechanic to attach these cards to opponents creatures, you would have to do something like the Cranial Plating cycle, writing out "X,: Attach this equipment to target creature your opponent controls", in addition to having an equip cost that could only be used on your own stuff.
It's overly complicated and confusing and probably powerful in limited that the only place for it is supplamental product, and I really don't think there is any demand for this type of stuff
When THIS enters the battlefield attach it to target creature an opponent controls.
When THIS enters the battlefield take control of target creature an opponent controls until end of turn. Equip 4
You don't need have to make it able to switch among enemy creatures it enables itself the first time and otherwise you have to find ways to use it.