I'm wondering if the trees roots have breached the bottom of the smart pot...my best suggestion is to get a moving blanket, and a pallet.

Never done this before but i would possibly lift it onto a pallet. Then either get people to help carry the pallet or rent a pallet jack to get it onto a pickup truck. I would guess that the larger smart pots are hard to lift without the pallet, they cave in unless you have even pulling from at least 4 sides.

couple 2x6 's and make a ramp to your pick up truck or use them 2x6 nail some 2x4 size of your bottom place on top of 2 x 6 and have 4 people lift it up
dolly skate board lol so many ways really
your biggest issue is if roots broke through and she is in the ground

Uhaul truck with ramp, baby pool, packaging Saran Wrap, a gallon of baby oil to lube, winch. Consider it done! :)

Get 4-5 pvc pipes, or abs pipes and roll it.

Even using the frontloader on our tractor, moving the 100gal SPs without taking some soil out hasn't been in the cards. I think that IF you can get the edges raised you can use a combination of Bulldog's idea and the pallet/boards route.

Are you saying it's planted??? I honestly don't see that going well unless you cage it all somehow. Those pots are soft and don't hold their shape, I can see during the process of moving it how you'd shred the root system apart.

I had to move 80 hundred gallon smart pots with four foot tall plants in them last year. How I did it is like this. You take a thick four by eight piece of plywood. On one side of the piece of plywood you drill three one inch holes evenly spread out on the 4 foot side of the plywood . Then cut a couple pieces of thick rope in 3 foot lengths. Put the rope through the hole and tie it in a loop like your making handles to pull a sled. Now get 4 strong men. Let the pot dry out as much as you can. Have all 4 guys try to scoot the pot onto the other side of the wood away from the rope handles. (This is the hardest part) then use all 4 guys to pull the handles and try to gain some momentum to where you are trying to pull it. You could probably slide the wood right up the rails on u haul ramp and into the truck. Keep momentum and if the ground isn't flat you might want to use a quad.