I always thought Ingrid's best rivalry was Lenka. I remember reading once that Ingrid had recruited Lenka. Turned out they were very evenly matched. Lenka had a scissors hold that Ingrid couldn't escape and Ingrid had a head lock that Lenka couldn't do anything about. After a while, they started having matches where those two holds weren't allowed because both got so frustrated with each other.
Melanie was always my favorite DWW girl. Pretty, petite, and hyper competitive. Not afraid to take on girls bigger than her. Wasn't afraid to bend the rules a little if it gave her an advantage and wanted to win so badly she'd sometimes cry when she lost. Luzia, a beautiful girl, was her biggest rival at the time. And yes, Luzia did make her cry a time or two.