Only the ones that actually get mentioned in comics, so no examples like Batman knowing 21746124712836 unspecified styles or Captain America being adept in "everything".
In Fred Perry's Gold Digger, Senadra created the Shun school of styles by fusing elven and dwarven martial arts. Each later master of the style creates their own variant, like Master Leep's Shun Leep, and Julia Digger's Shun Diggers (she trained in Shun Leep, then when she graduated and started her own Dojo, that's the traditional name scheme). There's a number of other characters who thus follow any of those, or multiple (Britanny Diggers and Gar Silvear both learned from Julia, but back before she was officially a master. Carla and Luan started under Leep then moved to Julia).
It's got something of a jeet kun do-esque 'whatever works' philosophy, but includes a lot of specialized strong moves with vulnerabilities relying on skill in move reading to know when to use them, and has a few unique sacred techniques like Renewing Breath, Master Blow (which is a 'put all your strength into a single attack' thing), and Leep Palm.
Also in GD, Ayane Anno uses a combination of ninjutsu and capoeira.
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DC, Black Canary is most famous for her Judo skills. Wildcat, Boxing, who he's also taught to Black Canary and many others.
GI Joe, well, lota ninjas there.
Transformers, Bludgeon is famous for his mastery of Metallikato.
It's not like there's a reason to 'disqualify' him, is there? I mean, we're talking 'what arts does someone specifically know,' not 'who's better.'
Lesse, when Batman was going through martial arts with Cassandra, he started with Aikido and ended with... agh, I forget what, but it was alphabetical.
Barbara Gordon taught Cassandra Escrima, so they both know that one.
He's such a forum joke, someone will soon post he knows not only every MA in the universe in all timelines, but also MAs that don't even exist. That's why I want to avoid him Too much hax.
I fear for Wally's life in KK vs. Flash thread, btw.
Do you have scans in your respect thread? I know Sue sparred with Iron Fist, but don't recall Reed doing anything MA-related.
Gambit and Moon Knight studied it, too. And perhaps Tarantula (Rodriguez), but don't recall whether or not it was specifically stated it was savate he was using.
Pic won't show up, but the site still allows it to be dl-ed. Credit goes to Deadline/Phantom Zone, taken from Punisher's rev. respect thread. Pretty great feat for both, showing their versatility as fighters.