I thought about a couple of ideas for different mounts that could be added
Land Mounts:
Galvantula (I would buy this one in a heartbeat)
Metagross
Motorcycle
Surfing Mounts:
Raft
Lotad
Blastoise (or anyone from that evolution line if it's easier)
Player Swimming (honestly not sure if it can work but figured I'd mention anyway)
Figured other people would also have some ideas too
Kinda curious to see what you guys come up with