Pixelmon Mod

Make Gengar when you ride him, you fly and not just go on ground. Gegnar has the ability levitate after all and you can see him fly in the anime.

It had the ability Levitate - until it was removed after Gen 6.
I'm ambivalent here. It does float on occasion, but straight up flight feels a bit far. They tend to stick close to surfaces to phase through, and their body doesn't really suggest flight capability even at the second or third look...

If Gengar becomes a flying mount, then Aegislash should definitely become a flying mount as well. In the movie Diancie and the Cocoon of Destruction, Argus Steel and his daughter Millis Steel used Aegislash and Doublade as flying mounts. Currently, Aegislash is a land mount and Doublade can't be mounted.