Legends of Osai: Thunderbird

Fulguroc, the Thunder Bird pokemon
Fulguroc is a very large electric-and-flying type pokemon allegedly native to the Osai region. It is a legendary creature that very few people have ever seen. Fulguroc is the name given to it by settlers - its real name is kept secret by the native Osaigon, who believe that they hide themselves from the settlers' descendants even today. Fulguroc can raise howling winds and cause avalanches but it is not an evil creature - it is said to guard places of great power and importance, so it only unleashes its powers to protect them from interlopers. If a storm blows up suddenly on an otherwise clear day, it is surely the work of fulguroc.