Spiritual Adaptation: In an essence Switch is Buffy The Vampire Slayer meets Avatar: The Last Airbender.
Foe Yay: Hauser and Kienzle (two German co-moderators from a show about politics. One of them's a leftist, the other one a rightist. Switch! exaggerates, but didn't pull it out from thin air.)
Ho Yay: Hal/Kai in particular. Hal can be considered bisexual which makes him a walking Ho Yay magnet. He and Kai are extremely close, to the point where there is no evidence denying that they could be an item. Hiki/Kagiyama also counts, especially in some of the official doujinshi, and there are many other examples throughout the series and its side materials.