Metroid, Kamen Rider, and all the characters and elements, (C) Nintendo, TOEI, TV Asahi and Ishinomori Productions respectively.
Continuity and Placement for each characters:
Samus: For Samus, as Metroid Fusion is chronologically the latest entry of the Metroid series, the events of the story take place after Fusion itself.
Kureshima brothers: For both Takatora and Mitsuzane, the events of the crossover story takes place after the Movie Taisen Full Throttle. Micchy in the other hand, was last seen in Gaim Gaiden: Knuckle.
Gou/Mach: For Go, it takes place likewise after the Chou Movie Taisen Genesis.
Takeru/Ghost AND Makoto/Specter: Most events of this story takes place during and within Kamen Rider Ghost itself.
Rating: M due to probable scenes of graphic violence, blood, and/or nudity; especially in the Trans-Fusion sequences.