If I lift or drag a mobile goal around while stacking cones on it, would it count as possessing more than one cone?
As far as we know this is legal.
As long as you are touching one cone at a time, you are good.
That doesn’t sound right. Let’s say you’d carrying a mobile goal with 5 stacked cones. Now you touch only the middle of those 5. That cone is no longer considered stacked. That means the two nested on top of it are also no longer considered stacked. So now you possess 3 cones, in violation of the 1-cone limit.
When carrying around a mobile goal with stacked cones, it is important that you only touch the top cone (which allows the placing of cones on the stack) or touch none of them at all if you possess another cone (such as picking another up to move onto your stack).