ive discovered a really really simple way (but costly) is to find someone that willl let you use/use for you a forklift truck. You need to brace it underneath to lift it and a suitable vehical for driving it around in.
realy extortionate (sp?) options aside, the most common is to get large buckets/bins for large fish, lots of baggies for smaller fish. take only the water needed by the fish and empty the tanks and get moving as fast as you can.
in the case of hyper-water-senstive fish, its also advisable to then take alot of tankwater, 5 gallon jugs from local hardware stores etc should help with that.