You can like all side companions. You cant buy El toro kan po ETC like all companions for everyone you cant buy them. but side companions that don't talk in story you can.
Well, Kan Po isn't for everyone, only his crown counterpark is, Keisuke Yagi, but yeah, I see what you're saying. Just remember though, for crowns sake, try to strategically buy Companions, not with your eyes, but with your mind :)
Actually, to correct you, it is possible to purchase Froggo Villa from the Crown Shop. However, in order to purchase him, you must first defeat him. Not meaning to be rude or anything! Ambitious Natalie Brewster