to the Forum!!
We need a little more information to go on, in order to provide any recommendations:
What is the hardness (GH), and pH of your Tap water?
What are the dimensions of your tank? You say it is a column tank? What is the diameter and height of the tank?
Unfortunately, the shape of your tank may limit what you can keep in it. A column shaped tank is not an ideal shape for most fish as it doesn't provide enough room for back and forth swimming.
Also, your list includes both soft (Neons and Cories) and hardwater fish (guppies) that might not do well together. Ultimately it is the GH and pH of your Tap water that will determine what types of fish you can keep.
I suspect, that based on the shape of your tank, that it may only be suited for keeping shrimp, or very small/Nano fish? Or a single Betta.
I would definitely not recommend Cories, as they are a shoaling fish that does best when kept in large groups, and they are bottom dwellers. In a 15 gal column shaped tank there likely would just not be enough of a footprint (floor space) for a group of Cories.