Well we know nearly know nothing of him, from the 5 kages we know second to least about him (we know least about Tobirama). Obviously he has more then one or two elements, and many other ninjutsu's; possibly S-classes. Even with what little we know of him right now, we can say he's top 10, which can portray how strong he would be once we know all about him. But there's a difference between 'not having' and 'not showing', and Minato has 'not shown'.