are there anyother aeons that have extras like valefor

Nope Valefor is the only Aeon in the game who has an aditional overdrive.

how do you get valefors extra limit...is it right near the start of the game in besaid???

It's in Besaid. You just need to find a girl who talks about a dog who found something and then look for a dog in one of the buildings. Talk to the dog to get Energy Blast. You can get it right at the beginning of the game, just by going back into Besaid right after first leaving the village to go to the ship. If you go back for it later in the game, Dark Valefor may be blocking your path depending on which version you're playing.

yeah

i ahd to take dark valefor down to get it...

the bitch...

he was a whore to take out

I got it and I have never used it yet. My old over drive did 9999 soooooo. I am guessing it does more than that.

Whether something does more than 9999 or not is based on whether or not an Aeon has been powered up to Break Damage Limit. Powering up Yuna's Nirvana with the Moon Crest will allow all of Valefor's attacks to have the possibilty of breaking 9999 damage, including Energy Ray. Energy Blast is most useful if you get it right at the beginning of the game by going back into Besaid before leaving on the ship because at that point it'll do quite a bit more damage than Energy Ray. But later on, it's not necessarily any more useful than Energy Ray, depending on what Valefor's stats are and whether you have Break Damage Limit. Of course, that late in the game, Valefor isn't particularly useful anyway.