Edit 12/20/2018
I figured it out! Man-At-Legs can sometimes choose to ignore captains, and instead only targets Pikmin.
Check out the attack patterns at 2:11 and 3:26
While in the Hole of Heroes, I noticed that my usual strategy of circling Man-At-Legs' feet with a second captain did not always work. After some investigating, I found that Man-At-Legs seems to have two distinct patterns for attack, though this is the first time I've ever seen such a thing. Could Man-At-Legs have per-cave hard-coded modifications similar to the Empress Bulblax and Burrowing Snagret?
Man-At-Legs also seems to have an affinity for the center platform. More-so than usual...
