Final Fantasy is full of many different iconic summons, from Shiva to Ifrit, and every Final Fantasy fan has their favorite. With that, however, comes discussions of which summon is the most powerful. That answer varies from game to game, but a summon that will often get brought up is Bahamut. Bahamut is one of the most prevalent summons in the Final Fantasy series, having appeared in each mainline game except for Final Fantasy II. His Megaflare, or his upgraded Gigaflare or Teraflare, is devasting to anyone who stands in its way.
Source:https://www.cbr.com/every-bahamut-in-final-fantasy/