Our toddler bows are a larger layered version of baby bows at 2-21/2 inches in diameter. The pinch clip on these bows is half lined (see clip styles and sizes) which makes it easier to pop through a ponytail or bunches. A fully lined clip can of course be made if you prefer but this wont go through a ponytail as easily.
Another option is to have the bow on a ponytail elastic. You choose which is best for your little ones hair.