In the first game, Joe wasn't noticed by Chugga until the Distant Spring, where he was very useful. He helped hatch the Smoky Progg and hid until Steve killed it. Also in the Distant Spring, Joe was temporaily turned into a yellow pikmin for a mission. He was captured by Emperor Bulblax in the finale of Pikmin and was saved by Bob.
Pikmin 2 Edit
In Pikmin 2, Joe became much more famous and helped stopping the Man At Legs, and The Waterwraith.