Moving every few years isn't that big of a deal with a desktop that you build yourself, because you can make it light/portable if you want.
But if you just want portability in general, then a laptop will be good.
That will run Dolphin, but it won't run Dolphin in a good environment. The Intel CPU and Nvidia GPU both share the same heatsink, so when one gets too hot, both the CPU and GPU will throttle back and slow down. You will want to get the ASUS ROG, this guy: http://www.asus.com/Notebooks_Ultrabooks/ASUS_ROG_G750JX/ as the CPU and GPU are on different heatsinks and fans.
But if you just want portability in general, then a laptop will be good.
That will run Dolphin, but it won't run Dolphin in a good environment. The Intel CPU and Nvidia GPU both share the same heatsink, so when one gets too hot, both the CPU and GPU will throttle back and slow down. You will want to get the ASUS ROG, this guy: http://www.asus.com/Notebooks_Ultrabooks/ASUS_ROG_G750JX/ as the CPU and GPU are on different heatsinks and fans.