An ideal pot would be at least 5 inches deep and be well insulated. Venus fly trap roots tend to grow almost straight down and they appreciate a good amount of depth to their pots, but do not require much horizontal room. In general, the deeper and larger the pot, the better a flytrap will grow because it provides a lot of room for their roots to reach down and the larger volume of soil allows for a more stable soil temperature.
Simple plastic pots are cheap and make good homes for Venus Fly Traps. Make sure that the chosen pot has holes in the bottom to allow the water to run out and prevent any mineral build up in the bottom of the pot.
Any pot that is porous should not be used for potting a Venus Fly Trap, such as an unglazed ceramic pot. Over time, unglazed ceramic pots will leech minerals into the soil and this can be potentially fatal to Venus Fly Traps. Also, unglazed ceramic pots are porous and therefore will absorb water and any minerals that are in the water, thus help holding these impurities in the soil instead of letting them be flushed out.