They're sidekicks who work under Gang Orca, referring to him as "boss".
During the Hero License Exam, they used costumes specifically prepared for it. Each sidekick was also equipped with a Cement Gun and a power suppressor. In addition, they were not allowed to use their Quirks.
Those sidekicks composed the main antagonist group used during the Hero License Exam Arc, simulating a terrorist attack. Equipped with Cement Guns, they attacked the test takers during the second half of the exam, under the orders of their boss.