Nightly is a shady, duck-like character. Not much is known about Nightly, except that he is an expert at collecting information for his clients, Birdy being his main client. Nightly is the source of all information regarding the Hige-Hige Bandits, Mighty Bomber and eventually Max for Birdy throughout the series and is often seen meeting with him. He always wears a trench coat, hat, and sunglasses to hide his appearance.
[Source: Bomberman Wiki]