After browsing his beat 'em up tag and reading most of the 29 articles within, here's what's salient. I also checked out some of his , and while they are neat, they don't apply much to what we're discussing.
History of beat em ups. He gives a basic classification of each era, but nothing concrete to go on from what I can tell. Shouty noted that TMNT was missing, and Fox asked why Dynasty Warriors wasn't on here if Devil May Cry was.
http://aztez.com/blog/2012/08/23/the-hi ... at-em-ups/
Here's something Shin Nekketsu Kouha doesn't have: mash flow. That is to say, pressing buttons in sequence to string along combos.
http://aztez.com/blog/2011/01/29/the-mash-flow/
Evaluating beat 'em ups. This has more to do with latter-day games in the ilk of Devil May Cry.
http://aztez.com/blog/2010/12/03/evalua ... at-em-ups/
Beat 'em up sheet music. I haven't read this yet, but it looks promising.
http://aztez.com/blog/2011/03/19/beat-e ... eet-music/
Skill divisions of players. Scrappers are button mashers, warriors learn basic means of expression, masters own an engine. I am definitely a scrapper (maybe a warrior if we're talking Sonic Heroes).
http://aztez.com/blog/2012/07/31/the-sk ... p-players/
Combat accessibility fork. The role of cancels in making a game accessible. Shin Nekketsu Kouha really only has one cancel--from a guard into a guard attack--right?
http://aztez.com/blog/2012/12/13/a-comb ... lity-fork/
Links to great articles about combat. I haven't read any of these so far.
http://aztez.com/blog/2012/12/26/links- ... re-combat/
Mechanic analysis in video form. Haven't watched these yet.
http://aztez.com/blog/2012/12/26/mechan ... ideo-form/