I doubt it - check out Serebii.net, the 4th Generation section.

Not only does it look like Chansey and Blissey will be returning, but there looks like there's gonna be a Baby version of Chansey, which looks like a chibi-Chansey-Igglybuff combo in a cereal bowl.

Also new to the family is a cat with a boomerand for a head - let's throw it and see what happens.