Pomegranate trees usually have thorns and are grown as a bushy shrub. That being said, pomegranates can be trained as a small tree ideal when growing in a pot. 
Pomegranates thrive in areas of warm, arid conditions. That being said, pomegranate trees in containers can either be grown indoors given sufficient arid provisions (and a sunny spot), or outdoors during part of the year and moved indoors if cold snaps are imminent. They are relatively hardy and will bear fruit within the second year. 
They require full sun exposure; aboundant water  about once a week, possibly more often during peak summer months. Prune out any crossing branches or shoots to three to five per branch after the tree’s first year. Prune out any dead or damaged limbs in the late winter.Read more at Gardening Know How: Container Grown Pomegranate Trees – Tips On Growing A Pomegranate In A Pot https://www.gardeningknowhow.com/edible/fruits/pomegranate/pomegranate-in-a-pot.htm