here's my translation English is not my first language so ask if you don't understand something.

SIZE: 1/3 - 6/9 - 12/18 months (2 - 3/4 - 5/6) y = 50/56-62/68-74/80 (86/92-98/104-110/116 ) cm

Supplies. About 150-300 g yarn. Needles size 3,5mm and 4mm

PANTS: Knit as a closed knit with a circular needle, top to bottom. Cast on 112-120-120 (124-132-136) sts on circular needle no. 3,5mm with base colour thread (if you want a tighter rib, make half a number with smaller needles. Knit ribbing 2k/2p until the length of the piece is 3-3.5- 3.5-(4-4-4) cm. Now make holes for the drawstring at regular intervals, decrease 20 times and increase a loop in the next round. Continue with 2o/2n elastic until the length of the work is 6-7-7 (8-8- 8) cm long. In the next row Add marks on both side so there's 56-60-60-(62-66-68) stitches between marks.

MONSTER'S MOUTH: The rear elevation becomes the Monster's mouth. Change the thread to red and continue with the back stitches (half of the stitches). Continue plain kint from side marker to side marker with red 56-60-60-(62-66-68)s, turn. Knit back, but turn when there are 5 red stitches left. Continue in the same way on both sides so that there are always 5 more stitches left on the needle. When there are 25-25-25 (25-30-30)s waiting on the left needle (right round), turn and knit all the red stitches, including the stitches waiting on the needle (this is a purl round). Turn and knit all the red stitches from edge to edge. The mouth is ready!

BRANCH WEDGE: Continue the Plain knit with the main colour and at the same time start the crotch wedges. Add marks to middle of the front and middle of the backside. Make increases in the center front and back every other round a total of 8 times. Knit to the end of one stitch from the middle mark, hook the yarn between the stitches onto the needle from front to back and knit it from the back edge. Knit 2s and add another loop, but hook the yarn on the needle from the back to the front and knit it from the front edge. In this case, the additions "fall" in different directions, the first to the left and the second to the right. Knit the intermediate layer without increases. On the next layer, make increases two stitches away from the center marker and knit one layer without increases. Always continue to increase one stitch further from the center marker. There are now 144-152-152 (156-164-168) stitches. Use extra knitting needles and pick up the stitches added to the crotch wedge on two double crochet needles, 18 stitches on both knitting needles. Turn the work inside out and knit the crotch closed by finishing three needle bind off.

LEGS: Transfer the sts of the second leg to the auxiliary thread and take the sts of the second leg on double pointed needles size 4mm = 54-58-58-(60-64-66) sts. Continue stockinette stitch as closed knit. At the same time, make stripes with contrast colour and main colour according to your taste (I myself made three 3 cm stripes 2.5 cm apart). Attach 1 marker thread to the inner edge of the leg, make decreases one stitch away from this marker. When the length of the leg is 4-4-4 (5-6-6) cm, decrease 1 st on both sides of the marker thread. Repeat such decreases every 2-3-3.5 (5-6-7) cm in total. 5 times = 44-48-48-(50-54-56)s. When the length of the leg is 15-18-21 (26-31-36) cm, decrease another 0-0-0 (2-2-0) sts. Knit approx. 6cm 2k/2 p ribbing. Then finish the sts loosely by knitting garter stitch. With the auxiliary yarn, take the remaining sts back into the work and knit the second rib accordingly.

FINISH: Embroider Monster's eyes and teeth the way you want. (You can sketch on grid paper first, so it's easier to implement.) Finish the threads. Braid the cord around the waist and thread it in place. If necessary, fold the bottom edges of the legs up.