So what you are saying is that... All the tablets and phones that have released over the past 8~ or so years with HDMI output are Hybrid devices? Good to know.
You don't need to play a device "on the go" for it to be classed as a hybrid device.
No. Distance isn't relevant. - As long as you do not have any cables that tie you down so you can move about freely.
I am also using the definition of a "hand held". - Because. You know. It's a screen you hold in your hands. Just like a Gameboy/DS.
Again. I suggest you go take a look at the dictionary definitions I provided earlier and then take a better look at your example.
You want to go definitions here
"A handheld game console, or simply handheld console, is a small, portable self-contained video game console with a built-in screen, game controls, and speakers. Handheld game consoles are smaller than home video game consoles and contain the console, screen, speakers, and controls in one unit, allowing people to carry them and play them at any time or place."
The Wii U's portability doesn't fall under this no matter how hard you want to loosen the definition of portable you know why? Because it's not self contained and can't be play anywhere therefore it's not a hybrid Handheld/Home Console as it can only be played at home no fallacy or loose definition you pull out will change this fact.