Rushing Beat Ran (Brawl Brothers) should be studied as how not to design a beat 'em up, or really a game in general.
The game's so devoid of ideas (it's clearly aping Final Fight) that you would at least think it'd be refined in some way. Nope. Walk right. Fight 3 enemies. Walk right. Fight 3 enemies. Rinse & repeat until the end level boss. Rarely will a stage contain anything interesting. The most (and only) fun I had was outrunning the camera to kill myself by sprinting off a high-rise.
Watching grass grow is less repetitive than this.