The Pilotwings universe refers to the Super Smash Bros. universe's collection of characters, stages, or other properties that hail from the games in the Pilotwings series.
In Super Smash Bros. Brawl
Several stickers in Super Smash Bros. Brawl hail from the Pilotwings universe.
In Super Smash Bros. 4
Stages
Unnamed Pilotwings stage: There is to be a stage based on the Pilotwings game for SNES in Super Smash Bros. for Wii U.