The rarest ones you have are most likely Sweet Notes (the hot orange-red pony with frizzy yellow hair and a TaF symbol), Sunny Bunch (the pink pony w/a green mane and a 3D saddle), Baby brother + sister Apple Delight (the little white TaF baby ponies that look similar, and your seapony. There also may be a few in there that are rare and I just don't recognize. (And please don't customize Baby Bouncy, the yellow baby First Tooth pony w/blue hair! She's kind of rare too, and way too adorable to customize, at least in my opinion!)