It is a bad idea to use pots made with limestone or any other calcium-based ore. However, this does not happen all that often. Most basic pots will work so long as you stay away from the fancy display ones and the ones that have been painted.
To plug up the hole in the bottom you can use aquarium silicone, but wait 24 hours before placing such a pot in an aquarium. Also, it is a good idea to soak any pot for a least 24 hours before placing them in the tank. This gives the aquarist the chance to test what effect the pot has on the water chemistry. (Use tank water and an airstone to circulate the water in the soaking bucket.)