I know. And yea I regret saying that (I was tired at the time probably, I have been really tired recently). Regular Bahamhut's Mega Flare is more powerful than Oner's Light Mega Flare or Reno's Dark Mega Flare (plus Neo Bahamhut, which is their current summon, uses Giga Flare, which is something that shall be employed only if shit gets really bad since that can really wreck something). 

Also in KH these higher level spells aren't as powerful as they were in FF mainly cause the combat is alot different, like Mana recharges for instance (which is why characters don't seem as tired after using big giant spells) and spells like Ultima or Meteo, while great on specific opponents, are really more meant for groups rather than single targets.