From the Super Mario Wiki
Dreamcap Captains are purple, supposedly layered Capnap-like creatures that appear in Mario & Luigi: Dream Team. In the field, Dreamcap Captains wander around aimlessly if undisturbed, and charge at Mario and Dreamy Luigi upon sight.
In battle, Dreamcap Captains and Dreamcaps fight in together in hordes. If all the Dreamcap Captains are defeated and any Dreamcaps remain, the Dreamcaps will huddle together and one will run away with each turn. If all the Dreamcaps are defeated and any Dreamcap Captains remain, they will summon several more Dreamcaps to then be able to attack. The group may also charge towards Mario as a pack, whom Mario must move out of the way or jump over in order to avoid the attack. They may attack from the background, charging towards Mario in rows, which Mario must jump over or on to in order to avoid the attack.
Stronger versions of Dreamcap Captains called Dreamcap Captains R appear later on in the game.
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