John GBA is a much cheaper GBA emulator for Android. It uses its own XML format for cheats. This repo contains a script to convert other cheat formats to John GBA's format.
The format is in XML. The root element is <cheats>, then it has a list of <item> elements. Each <item> element has disabled, name, and code attributes. The disabled attribute is either true or false. The code attribute is the cheat code, and &# is used to represent a newline.