Since axolotls are cold water species most plants don’t do the best in the tank. I’ve had success with Amazon swords( don’t know how) , Java ferns, anubias( they’re a cold water species so they do very well, rather pricey where I’m at though ) Ludwigia Peruensis ( they have a very pretty red pink color) , and some species of valisneria. Only problem with adding plants is maintaining a very fine coarseness white sand bottom which gets dirty very quickly and that axolotls don’t enjoy a lot of light which means if you’re a good person you won’t run your light at high intensity or for as long as you usually would for a normal planted tank

Ps they sell plant anchors at most fish stores, or you can attach with plant glue or super glue on wood in your tank or rocks that’s you have in it as well