Dreamy Luigi is an exact replica of Luigi except that Dreamy Broque Monsieur states Dreamy Luigi as "more handsome" and "slightly taller" than the actual Luigi. However, this could imply on how Luigi thinks of himself as.
Unlike the regular Luigi, Dreamy Luigi doesn't physically fight alongside Mario during enemy or boss fights but he does after Mario lands a hit on enemies. He could also do several Bros. Attacks, named Luiginary Attacks, with Mario. Dreamy Luigi can also split into numerous of clones of himself which are called Luiginoids.