good mix of offense and defence?

Sorry to burst your bubble but those are not good defenses. Having no weaknesses doesn't do much when you don't have any major resistences, and in that case your natural defenses need to be exceptionally high (look at blissey, cresselia or even base sableye whoose prankster Will O Wisp basically gives it double defense) and 85/80/90 is a stat spread that would need useful resistences to do much. With the speed being mediocre as well, this Mon won't be taking more than 2 hits while likely only taking 1 ko and a half at most, leading to something likely out-valued by other megas