To get it evolved you have to hurt yourself till it heals you. Best way to do that is to stand in the campfire

Thses cute little creatures will be healers in wild and they will still be able to heal in the wild which is how there tamed

Will they be fully aquatic or amphibious? ( this is a concern for me because the tidepup is based on the axolotl and they are fully aquatic) i hope that they dont do the fully aquatic path to keep it useful but if they do they should at least make it slower on land to still keep a realistic amphibious feel to him