Those based of Aquatic life forms. Beings like Undyne, Onion-San and Aaron all fit in this category.
“Undyne is the leader of the Royal Guard and a boss in Solartale. In appearence, She is very...Undyne/Solartale
“Undyne is the Rolereverse version of Asgore. She is a very kind monster who likes gardening...Undyne/Rolereverse