As an Australian, I'd say a pony would be fine!
Just no perfume, meds, unprocessed natural food like meat or fruit(?) no soft drinks or liquids they have the potential to explode, I cant think of much else but I can research more if need be!
Candy, savoury snacks and powdered drinks are fine (just make sure any powder stuff is wrapped in a bag so if it explodes you, your friend or pony won't get dirty.)
Meds like strepsils is fine, just no bad drugs like cocaine or aluminium cream tube stuff.
Also, I don't think the postal force people would appreciate it being gift wrapped. You might be able to get away with it if the shipping areas are the original box (If that makes sense)