I respect your opinion, but,
Latios+Latias Moveset are more offensive!? No sorry, i
think they have a defensive movepool.
Calm mind, defog, roost, healing wish, reflect, light screen, magic coat, recover, refresh, roar, tailwind, toxic, thunder wave, wish, heal pulse, helping hand.
Offensive: Dragon Dance (Special Attacker with DD :P) and Clam mind?
Wanna hear more? :P
Pokemon like Hydreigon, Volcarona have a offensive movepool, not Latios (I think)
Latias, Gliscor and Scizor are already in OU by usage. (Need a bit more). Also, mega Latias is better than Mega Latios because it has a better defensive stats so it can use calm mind more, and doesn't waste stats on Atk like latios-mega