>>11621038 (OP)
I'd say anything that's PVC and easily washable or has removable clothing, with the size & scale up to you. 1/6th Scale "Soft-Body"/Seamless figures SEEM like a good idea at first, but you have to be careful not to damage the body by having the wash water too hot, or forgetting to rub a good-grade corn starch back into the "Skin" when it's clean.
PVC Statues or something like a Snail Shell action figure on the other hand is fairly straight-forward. The key would be hand-washing any clothes they might have... Honestly, I'd look in /gif/ for a thread on the subject and just be friendly when you ask questions.