If you are to boil a pony past the neck seam, take the head off. Water can seep in. If you are trying to clean the insides of a pony with boiling water, take the head off. While water can seep in, not enough will get in. For pindot, just place the affected area in hot water for about a minute and scrape. One you feel the vinyl getting harder, reheat it
Don't boil glitter symbols and don't use OxiClean on them, the glitter will come off. And you don't need to use OxiClean for cleaning ponies, just use anti bacterial soap and scrub. I'm not an expert with using stuff like OxiClean with ponies, so I'm not sure if it would be okay to use laundry detergent. The best I can give you as a substitute would be soap