This is a sweater dress with some texture, made to fit a Made to Move Barbie.

It should fit a regular Barbie and possibly a Tall Barbie, except you might want to add some rows of stockinette somewhere.
If you want to make the dress wider (Curvy Barbie) or narrower (Petite Barbie) you need to cast on with a multiple of 5 stitches and perhaps eliminate some rows of stockinette.

You need at least one stitch marker to mark the beginning of the round and four additional (different markers) to mark where you will be doing decreases.