From the Superfriends cartoon:
Apache Chief-Native American
Samurai-Japanese
El Dorado-Mexican
Black Vulcan-Black
Not the best examples as they were little more than tokens religated to the back part of the story or even worse given some of the most idiotic storylines Superfriends ever had. Does El Dorado who has teleportation some form of telepathy, and illusion power fight an interesting villian? No. He gets stuck fighting some pathetic loser called Doll Maker who stole his gimics from DC's Toyman and Marvel's Puppet Master.
Apache Chief main foil for the Challage era was Giaganta who was in the comics was an genetically altered ape. If this was not bad enough his next major story had him fighting this cosmic giant who has added Earth to his marble collection.
Samurai didn't last long past the Challange season and was pathetic compared to such DC comic heroes as Rising Sun and Dr. Light (the asian one not that white guy who got his mind messed up).
Black Vulcan didn't do anything for mos tof the stories he was in. Now Cyborg actaully got some good stories but by that time the Superfriends cartoons were coming to an end.