We love multiplayer video games. Here's a few things to keep in mind if you want to bring one…
A lot of games have a save-game file on your system that unlocks special areas, etc. Your console might have a way to copy that to a memory card, SD card, or USB memory stick, so if you're bringing a game disc or cartridge, you can bring your save game along too.
Instructions: Wii U, Wii, PS3, PS4
On the Nintendo Switch, you can just bring your whole console's main unit … the only way to transfer save files is to move your entire User Profile to the other system, and then move it back afterwards, but you might as well just drop your system into the Dock instead.
On older consoles (Game Cube, N64, PSOne, PS2), just bring the external memory card.
Check with the host whether someone's already bringing the same console with him … it makes life a little easier when there aren't four Wiis in a stack with a mess of power and video cables to fuss with. (For the Switch, just make sure someone is bringing a Dock, at least.)