In the preview of Kamen Rider OOO Episode 8: Sabotaging, Having no Greed, and Being in a Break, we saw the glimpse of the four enemy Greeed's full forms. As of now, Gamel has the least number of Core Medals in his body.
Each Greeed has a total of nine Core Medals, two copies per each type (That is why, Ankh has two Taka Medals and Uva has an extra Kamakiri Medal.).
One thing that I noticed in their full forms is that their belts are colored gold, similar to Kuuga when he uses his Rising forms and his Ultimate form. It is still a mystery if Ankh might appear as well in this scene in his full Greeed form.
Based on the preview shot, it seems this scene might take place 800 years before the series started considering this scan from one of our earlier post.
Source: JEFusion
Source: JEFusion