Axolotls do not have any eyelids so any bright light can stress them.
They do NOT need Heating
Axolotls are cold water amphibians so room temp is fine or cooler. Anything warmer will kill them. NEVER use a heater in their tank or tub.
They do NOT need Filters
Axolotls are very sensitive creatures, they do not like fast moving water as that can stress them so the more still the water is the happier they are. It is much easier doing manual water changes.
They do NOT need Substrate
If you must have a substrate on the bottom of your tub or tank then make sure it is a very fine sand and nothing larger as they have a habit of sucking in anything they eat, so anything large can get lodged in their stomach and anal track causing a blockage and that can kill them. NEVER use gravel as that is extremely bad for them and kill them. Even sand can be bad as can cause impaction and ultimately death so its better to just have a bare bottom bank.
When it comes down to it decoration is for the benefit of the human more than the animal itself. The best solution is to have plastic plants that can be weighted down as looks good and also will not harm the axolotl.
What is not required
Remember Axolots are NOT fish so do not treat them like one
Is it a Fish? NO, Is it a Reptile? NO, Is it a Tadpole? NO......What is it?, It's an Axolotl