They are a race of bird-like aliens resembling eagles with bulbous beaks, large wings and brown and beige feathers. They all wear matching grey military uniforms complete with grey war helmets that have spade cards on them.
The Water Wingmen are soldiers specialized in aquatic combat and guard the many bodies of water surrounding General McGuffin's fortress.
The Psychic Battalion is quite possibly McGuffin's most dangerous known unit. The soldiers posses powerful psychic abilities that can warp the senses or create realistic illusions. They can recreate the dangers of McGuffin's fortress in order to intimidate intruders and if that doesn't work they will show their enemies their greatest fears.
"Wingmen" refers to pilots whose aircraft are following a leading aircraft in a formation.
During World War II, the soldiers from the 506th Parachute Infantry Regiment of the American 101st Airborne Division (who were known as the "Screaming Eagles") would paint the spades symbol on the sides of their helmets to represent good luck due to it being a fortunate hand in card games.
The fact that the Wingman resemble eagles might also be an ode to the Screaming Eagles.
During the Vietnam War, American soldiers believed that the spade symbol was a sign of bad luck to the Vietnamese people and so some soldiers wore ace of spades cards on their helmets as a sign of hostility.