Sidekick-itis
Sidekick-itis (Sidekick - eye - tiss), as coined by Lindsay Ellis, is a word for a phenomenon that occurs in (usually fictional) media, where said media has (or what is considered) to be an overabundance of "sidekick" characters.
"This movie has a bad case of sidekick-itis, even the sidekick has a sidekick!"