Gavan vs. Dekaranger was written by Dekaranger head writer Naruhisa Arakawa (Kaizoku Sentai Gokaiger, Kamen Rider Kuuga) and directed by Koichi Sakamoto (Kamen Rider Fourze, Zyuden Sentai Kyoryuger). The film premiered last June 17th in theaters and via online streaming.
[Source: Anime News Network (link 2)]