That being said, Kamen Rider Ghost will transform into Drive, Gaim, and Wizard while Specter will transform into Fourze, OOO, and W. If you notice a pattern, Specter transforms into the first three Phase 2 Heisei Riders (W-Fourze) while Ghost transforms the later Phase 2 Heisei Riders (Wizard-Drive) minus Ghost.
The Kamen Rider Ghost: Legend! Rider's Soul! will be streamed on Toei's official YouTube channel starting on January 15, 2016 with "Drive Chapter".
[Source: The Ghouly News Tumblr]