You can with a normal link cable
You can link up your PC to the CM100 by using an Ethernet cable or USB cord. Connect the Ethernet cable to the CM100 Linksys modem and the other to the Ethernet port on your computer or if you are using USB connect the USB cord to the USB port on the computer.
Purchase a link cable from your local game store and plug it into the link port.
you have to use a link cable
No it isn't compatable.
Yes.
You can trade pokémon by using a link cable between your GBA sp / GBA.
no there is no multi system link cord
http://www.amazon.com/Game-Boy-Advance-Link-Cable/dp/B00005BOS7
you can buy it on the google shopping link, but other than that i don't know. they also are probably sold out, but 1 link costs $5!
Yeah if the game supports it u need a cable to link them
if u have two gba games on a gameboy advance then you need the link cord to connect them if you have two games on ds such as Pokemon pearl and Pokemon platinum then when you just stand next to each other p.s. you go upstairs in a Pokemon center