Nickolas, welcome to the forum
Please take time to visit
www.axolotls.org if you haven't had a chance to yet. There is heaps of information as this site about axolotls.
Plants are totally safe to keep with axolotls! But some plants also may end up getting shredded by the axolotls if they are delicate. Others can stand abuse. Axolotls do not like a lot of light, but if they are used to some light, they can tolerate it if you put some floating plants at the top like duckweed or crystal wart to shield out large portions of light.
My tank has lots of duckweed covering the top. I have a nice big cave for my Axolotls to hide in, and also a shady tree root, but my Axolotls tend to most of the time hang out in the open as pictured even with my lights on. My guess is the duckweed really helps
And I also agree I wouldn’t get a sick Axolotl from the pet shop. I rescued the gold one pictured, and she had anchor worms and gravel in her stomach. She would bleed trying to push the gravel rocks through his system, and he would rarely eat. After a few weeks she dramatically improved so much that she eats very well, loves to swim and is very active now
Where abouts do you live? If you live in the united states, Michael Shrom visits the forum, and he usually has Axolotls for sale, or you can try to order some from
http://www.wardsci.com/Product.asp_Q_cm_E_1_A_pn_E_878252
They should still have some in stock from the axolotl colony, but I am not sure on that. Good luck!