When the subject of arcade beat-em-ups comes up, it's more than likely that two companies are going to be at the top of the list: Konami and Capcom. Between the efforts of the two developers, it was their work that really defines what we now consider the modern beat-em-up, even if they'd both approach the genre in different ways. Of course, Konami was hardly just a presence in the arcades alone, and while their console brawlers aren't their best efforts, at least a couple of them are worth trying out, as well.
What Konami did well, and what made their beat-em-ups so memorable, was their sheer spectacle. In most cases, a lot of Konami beat-em-ups were made from recognizable licenses. Pretty much any kid in the late '80s was going to recognize The Simpsons or Teenage Mutant Ninja Turtles, so they already had something that was going to pull players in right away. Combined with that is the fact that most Konami brawlers had room for four or, in the case of certain versions of X-Men, even six players at a time. It's those two things above all else that really bring in the great arcade memories, especially since the gameplay on most Konami beat-em-ups isn't quite up to the depth of Capcom's best work.
That's hardly a slight against them, though. True, only a few of Konami's brawlers take a lot more thought than mashing the single attack button you're given. But the way they're set up means that anybody can join right in and be at least decent at them, and even if you're not playing, there's always the thrill of watching your favorite characters like Wolverine or Homer moving around and beating up people. That's hardly all Konami would put out on the beat-em-up front, however, and there's plenty of originality to find in their library, and games like Violent Storm and Vendetta go into an entirely different direction entirely.