These characters were never officially made for MOTUC, but these custom Classics figures may help to complete your collection.

Lady Slither (by AC Toy Design) - magnetic tail attaches to torso for display: https://www.ebay.com/itm/134802342265

Hunga the harpy (by Rex Barja): https://www.ebay.com/itm/134802334804

Minox (by AC Toy Design): https://www.ebay.com/itm/134802326864

Lizorr (by Rex Barja: https://www.ebay.com/itm/134802331077