Hi KM, all scooters can be disassembled for moving, the issue is how much weight you can manage and for how long.
I have a 4-wheeled Pride Victory that weighs 185 lbs assembled, the heavies piece is a little over 50 lbs and I cannot manage that myself. It stays assembled in my garage and I use it for outdoors. Solid tires give me peace of mind. It can go almost anywhere, I have taken it across cornfields and into the woods with no problems. But, this is a big one, it's not as maneuverable as a 3-wheel and has a large turning radius. This one I call my bike, it's great for a lot of things but I do not find it practical as a PMV. It was expensive and if I had it to do over, I probably would not have bought it.
My portable scooter is a 3-wheeled Bruno Rio III that weighs 70 lbs. assembled (without arm rests or basket) and from what I hear, they aren't making them anymore but they can be found online for about half what I paid. I would definitely get another one if I were so inclined. The heaviest piece is 24 lbs. and I can manage the thing myself in under a minute each for assembly and disassembly. It has a 30-inch turn radius which allows me to dodge through almost any situation. I opted for solid tires and do not regret that choice.
The Rio III has been all over the U.S. by plane, boat, car and train and has done extremely well for me. It is not as powerful or fast as the big one, but it serves me well and rarely gets stuck (I do tend to push it to its limits).
It's very easy to fly with, the gorillas can literally pick it up and bolt down the jetway steps when stowing in cargo on a plane.
Matters to seriously consider:
-Look for one with contact battery terminals, this means that the battery pack has two recesses that expose the contact points and the battery is simply placed upon them as opposed to needing to be manually connected.
-The Rio III comes with a great battery pouch that has a handle for moving the batteries as a single unit, I recommend it highly.
-Think about the vehicle you will use to transport this thing, if it is a trunk, you will need the strength to lower the pieces safely and be able to lift them out of the trunk. It's a little harder than it seems since it's a breakable machine.
-The usable life of a charge as advertised is actually measured in the most ideal conditions at the lowest possible speed. Be realistic and understand that it's actually about half of that depending on the terrain.
-Make sure that your choice includes sealed or dry-cell batteries. Just ask, they'll know. I get my replacement batteries from Batteries Plus for about half the dealer/manufacturer's price.
-Understand that the batteries themselves are easily prone to damage/death from bumps or drops, you'll need to be mindful of how well you can handle them.
-Your batteries are temperature sensitive and need to be connected to a power source when left outdoors during winter. I would not leave them outdoors, mine stay in the slightly warmer garage, connected to power.
-Look for a scooter that can be charged when fully assembled AND directly at the battery pack. This is a HUGE matter to consider.
-I went ahead and spent $30 on a car inverter so that I can charge mine when driving, it makes a huge difference when planning a longer day with multiple stops.
-Mine has a nifty little trunk on the seatback that will carry my charger for times when I need to stop and charge up. I take it along any time I have a longer day planned and plug it in at meal times, etc. I've never been refused a plug anywhere (although at Arlington Cemetery, we had a matter of national security to get me the permission

).
-It's a bit more money, but I have never, ever regretted having a second set of batteries that I keep at the ready at all times.
I hope this will help you, I can honestly say that I would not have a 4-wheel for toting around primarily because the turn radius is so limited.
My strongest recommendation is to find a local dealer to understand how your needs and your body will be served with one of these machines. It's literally worth a day trip to know what you should and should not expect from these things.
For the record, I have no balance and can manage the 3-wheel without the armrests attached if I assert a good portion of sensibility about negotiating terrain.