Morning Musume and other movies

 Morning Cop (2000)

Cast:
Abe Natsumi
Fukuda Asuka
Iida Kaori
Ishiguro Aya

Nakazawa Yuko
Yaguchi Mari
Yasuda Kei
Ichii Sayaka

Rapidplayer or Dailymotion

Koinu Dan no Monogatari (2002)

Cast
Natsumi Abe - Furusawa, Yayoi
Dan - Himself
Akira Emoto
Takaaki Enoki
Maki Gotô - Natsume, Honami
Mieko Harada - Morishita Wakako
Kaori Iida - Okubo, Saki
Rika Ishikawa - Morishita Tomomi
Asami Konno - Matsushita Kanae
Yurina Kumai
Keiko Saito

Rapidplayer or Dailymotion

Pinch Runner (2000)

 Although they're given credit, Ishikawa Rika, Yoshizawa Hitomi, Kago Ai and Tsuji Nozomi don't have roles in the movie.  Almost every member of Hello! Project appeared in the marathon opening ceremony scene, divided in three teams.

Cast:

Minugishi Ayumi - Abe Natsumi
Hasegawa Sanae - Goto Maki
Kanzaki Tomoko - Yaguchi Mari
Matsumoto Michiko - Yasuda Kei
Hayashibara Maho - Ichii Sayaka
Sendou Reiko - Iida Kaori
Masuda Ikue - Nakazawa Yuuko

 Rapidplayer or Dailymotion

Tokkaekko (2002)

 Cast:

Morning Musume

Yoshizawa Hitomi

Ishikawa Rika

Kago Ai

Abe Natsumi

Yasuda Kei

Ai Takahashi

Niigaki Risa

Konno Asami

Ogawa Makoto 

Country Musume

Toda Rinne

Kimura Asami

Satoda Mai

Rapidplayer pt1. pt 2 or Dailymotion

Ore ga Aistsu de Aistu de Ore ga (2002)

Cast:
Hitomi Yoshizawa (Kazumi Saito)
Ryo Katsuchi (Kazuo Saito)
Asami Konno (Futaba Kazuo)
Rika Ishikawa (Akemi)
Mokomichi Hayami (Yamamoto)
Risa Niigaki (Keiko Kuwahada)
Makoto Ogawa (Miho Yamasaki)

Rapidplayer or Dailymotion

 Shinkansen Girl (2007)

Yoshizawa Hitomi as Nakano Hibari

Rapidplayer or Dailymotion