This tutorial is for a very simply woolly which fits all Monster High dolls without cat ears or similar. (Designing one for Clawdeen will be a small challenge! ^^) These woollies are a nice exercise for total beginners - my Pullips got almost a whole dozen of them before I dared try my first amigurumi. They can be easily modifed with colour changes or variations in the last row. If, for instance, in the last row you switch between single crochets, half double crochets and double crochets you get - depending on how random you make these changes - either a wavy rim or one that looks like it's melting, like icing on a cake. You can also make the ears bigger by adding another row, think up other ears or decorate the wolly with a pom pom, buttons or decorative stitches.
I used a size 3 crochet hook and the typical discounter yarn for size 3-4. If your woolly ends up too large use a smaller needle, if it gets too small try half a size larger. Yarn differs so much that for me instructions from the web most often don't work without hook size adaptions either. (That's the advantage about amigurumi, it doesn't matter for those!)
Abbreviations:
sc = single crochet
st(s) = stitch(es)
If you don't know how to make a magic ring you can chain 2 stitches instead and crochet into the 2. stitch from the hook.
Simple woolly
Make a magic ring, ch 1.
1) 6 sc in magic ring (6 sts).
2) 2 sc in each st around (12 sts).
3) (sc in next st, 2 sc in next st) *6 (18 sts).
4) (sc in next 2 sts, 2 sc in next st) *6 (24 sts).
5) (sc in next 3 sts, 2 sc in next st) *6 (30 sts).
6) (sc in next 4 sts, 2 sc in next st) *6 (36 sts).
7-10) sc in each st around (36 sts).
Join with a slip stitch, fasten off. (It's advised to test the woolly on the desired doll first. Depending on the hairdo 9 rows might be enough or in the contrary you might have to add an 11th row.)
optional bear ears (make 2):
Make a magic ring, ch 1.
1) 4 sc in magic ring, ch 1, turn.
2) Beginning in 2nd st from hook, 2 sc in each st around (8 sts).
Fasten off, don't cut off the thread but use it to sew the ears to the woolly.
There are three models total. For model 2 (the green one) crochet hdc instead of sc. For my woolly I had to add an 11th row - crocheted with sc in another colour - to have a good length.
For model 3 crochet dc instead of sc up to row 6, then add a 7th row of sc all around. In round 8, sc in next 2 sts and slip stitch in next 2 sts to get an even look, then fasten off. This only worked for me with very fine and elastic thread, else the woolly was too tight. The purple woolly was made in this style. But maybe my hdc and dc are just very tight since I'm used to tight stitches from Amigurumi.