Games designed for Single avatar Local Coop

One of my earliest gaming memories was playing a PC game called "Arctic Fox" at a friends house. It was a tank driving game with many keyboard shortcut commands. We played the game together where one of us would drive the tank and the other would work the weapons and radar system. My friend could probably play it by himself but let me be part of the crew when I came over. Being a late 80's game it had an abundance of keyboard commands so the weapons and radar person had more than enough things to do even if it was looking through the manual for what button elevates the main gun.

That long preamble was to sets up this game design question: What games out there play well as local coop with a single avatar? Either Pilot/Gunner on a single vehicle or some other combination of dissimilar but complementary roles.

I would like to make or play a game that would give a similar experience as Arcitc Fox for me to play with my son. I am reluctant to play coop games with multiple avatars because he tends to run his avatar off a cliff or trigger some other fail state then sit there board or demand my controller. The single avatar preferably with a helper mode would be a nice balance allowing me to play and my son to feel like he is contributing.

BTW we already have Mario Galaxy, but he hasn't figured out how to aim the wii mote at the screen.