I know we already have a GakiPon thread, however the Yin to GakiPon's Yang is MomoPon.
On a recent TV show, Mizupon apologized to Sayumi for liking Momoko more than her. Later, while Momoko was demonstrating the dance for her solo single the rest of Morning Musume was rather halfheartedly trying to do the rather embarrassingly silly dance but Mizuki was working it as hard as she could.
There are dozens of other examples, but I will leave it to others to fill in the blanks.