Hello there!
So I was thinking in my games I really want to have more options for animal companions and mounts. I was thinking at effective level 11+ druids, rangers, cavaliers, etc should be able to have exotic options. Like appropriate magical beasts or dragons. A druid with an owlbear companion or a wyvern riding knight would be pretty snazzy imo.
Anywho! I was wondering if anybody knew of any rules for such a thing?
Cavalier's have to choose normally for a medium character, camel or horse. A small cavalier can select a pony or a wolf, but can at level 4 choose between a dog or a boar. This said, other available options are there at the GM's discretion. Essentially, if the GM's ok with it, roll with it. The only prerequisites is that the companion must be suitable as a mount and capable of riding.
For Druids and Rangers, there's quite a few exotic options, although for ranger the more exotic ones are available primarily for the Beastmaster Archtype. Most of the options are seen here.
Additionally, if you look in the Pathfinder Campaign Setting: Path of Prestige, there is the prestige class called mammoth rider, which gives Huge sized companions, although the list is somewhat smaller, but can be expanded at GM's discretion. Mammoth Rider can be found Here.
Thanks for the information and links. I was hoping there might be something official along these lines. Could just estimate it but I'm not sure how to keep it balanced.