Digimon Frontier: Ornismon Fukkatsu!!
Digimon Frontier: Kodai Digimon Fukkatsu!!
Digimon Frontier: Island of Lost Digimon
デジモンフロンティア 古代デジモン(オニスモン)復活!!
The five digi-destined children stumble upon an ancient island inhabited by two different types of digimon; The Beast types, and the Human types. When they see two young digimon-a beast and humanoid-have become friends, they decide something must be done about the feud.
(Source: ANN)