What are the size requirements for creatures and their mounts?

[raidou]

Are there rules for what size category a mount needs to be for a particular rider? Can medium-size riders use a medium-size mount or does the mount always need to be one size larger than its rider?

[Mistwalker]

The mount must be a size larger.

[raidou]

Mistwalker wrote:

The mount must be a size larger.

I believe you, but I can't find anything that backs this up. There's this one tidbit from the ride skill:

ride skill wrote:

Fast Mount or Dismount: You can attempt to mount or dismount from a mount of up to one size category larger than yourself as a free action, provided that you still have a move action available that round. If you fail the Ride check, mounting or dismounting is a move action. You can't use fast mount or dismount on a mount more than one size category larger than yourself.

Saying "up to one size category larger" seems to suggest that you can attempt this on something smaller. Otherwise, it's just stating the exact same thing as the last sentance in the paragraph.

[Mistwalker]

The only evidence that I can find is on page 162 of the equipment section, mounts and related gear.

In the description of the Riding Dog they state that it is a mount to carry a Small humanoid rider. In the description of Horse, they state that it is a suitable as a mount for a human, dwarf, elf, half-elf or half-orc.

It is indirect evidence of the rule, but not conclusive. It could be a rule from a previous edition and I have just been carrying it along.

[Alphonus]

A friend of mine was wondering about this himself. He's writing up a cavalier for a game we're starting, but the mounts available to a medium sized creature at level five is extremely limited (horse basically being it).

In an effort to find something that would work, I was flipping through the bestiary and out of curiosity, began reading the description for the Pony. I found this part interesting:

"Ponies are smaller breeds of horses better suited to halflings, gnomes, and dwarves, but they also make fond pets for humans as well."

The important bit being the dwarf being listed as a possible rider for the medium sized pony...