Basically, to keep it simple, this is a system, which allows players who obtain mounts, to level them as a Hunter class would level their pet. Each mount obtainable has different trainable abilities to use for offense and defense in ground or aerial combat situations.
The system would require some work, but with the proper mechanic balances (yes, it requires MORE balancing), this could actually prove to be a very interesting system. Think about it! A full out assault from not only game NPC enemies, but also opposing players as you're riding through, or flying over Azeroth! Talk about game of the year!
Questions? Comments? Let me know what you think!
(Also for mods, feel free to put this in it's otherwise appropriate thread, if this is not the correct location for posting this)
EDIT: I see immediately, people are getting the idea that this is just like jousting. No it is not. This system would provide trainable mount abilities and perhaps talent trees that would allow you to customize your mount (like a pet) to your liking. This is not limited to buttons 1-5 and instead would offer a whole new action bar for mount-specific abilities. Players will NOT be able to cast primary class abilities while mounted.