The secret cards of Universe Mission 7 are pretty out there, aside from the obvious first one:
>UI Omen Grande Goku (w/ Zeno summon)
>Revived Demigra (w/ Enhanced Demon God transformation)
>Super Saiyan Gohan (w/ Family Kamehameha team-attack)
The first 2 make sense somewhat, since both are related to their respective storylines (Goku-Universal Disturbance; Demigra-Demon Realm Revival), but that Gohan card doesn't seem to be connected to anything.