Stilt Guys are, as the name implies, Shy Guys on stilts. They debuted in Yoshi's Island. In Super Mario Bros. X, Stilt Guys are usually Rex reskins.
List of SMBX Appearances[]
Return to Yoshi's Island
Super Talking Time Bros. 2
Sea Side Adventure
Super RMN Bros. 3
Super Puzzle World
Credit to Tonberry2k