Introduced in Generation Four, we were given companions that we would sometimes travel with. For wild battles, we'd be placed into a double battle with them, and only be able to capture a Pokémon if we knocked one out first. After each trainer battle, our Pokémon would be instantly healed. At the end of the area they'd disappear until you wanted to use them during the Multibattle type in the Battle Tower.
The question is, did you like being visited by a companion every now and then to complete a certain area with? Are there companions you would like to see come back? Did you think this system was entirely unnecessary, or did you think it was a welcome addition? Discuss!