My small leo and my larger leo live together.. they are on herbifloor.. thegrass pellet sub.. well.. the larger tort harlow has no problem walking on this but the small one really has to struggle.. im just thinking is news paper ok??
Newspaper is not a good substrate. They won't get good traction, their nails will not get worn down enough (you'd be surprised how quickly they can grow really impressive and sharp nails), and it won't hold any humidity.
Dirt would be a good idea for the two leos, or perhaps coco fiber bedding (like bed-a-beast). Some people use hay, but I don't think they little guy would get good traction on that. Even though leopards are desert tortoises they need some ambient humidity and they especially need a place that they can go with high humidity (like a rubbermaid bin filled with dirt, moss, etc)
Coco coir doesn't really have a smell and when its wet it sorta smells like fresh dirt but just faintly. It will definitely be better than alot of other things.
Both look like they are already starting to pyramid. They should be on a substrate you can keep moist to help create humidity and help prevent pyramiding. The bigger one is really fairly bad already.
To answer your question, yes, you really do need substrate. I would try to find something that you can moisten, to help with the pyramiding, like Maggie said. I like either orchid bark or cypress mulch. Neither of these has an unpleasant odor. When they are "new" they have a woodsey smell, that diminishes over time.
i rescued the larger one and i have only had the smaller one for about a month . I posted about my pyramiding concern prior but was told it wernt that bad xx