[Tidus2791]

Ok try some of these methods red gate

There's actually two enemies here, the Crawler and the Negator. Wipe out the Negator first, which is pretty easy. I just use Wakka to blast him out of the picture.

OK, now to the Crawler. Those Mana Beams are nasty. However, you have lots of "cannon fodder" - i.e. your aeons! Just watch when a mana beam is coming and toss an aeon in its path, making sure the aeon gets its uber-attack in first. Always go into battles like this with all of your aeons fully charged, so that you can do this technique.

You should be able to kill him relatively easily

OTHER METHODS

Before engaging the match against Crawler, buy about 10 Grenades and steal Electro Marbles from Aerouge or Gold Element. If you opened the chest leading to the Farplane, you should have received 8 Lightning Marbles by now. If you haven't used them yet, good.

Grenades should be used about 3-4 times to get rid of the Negator.

Strategy 1:

I suggest not to kill it rather focus your attacks on Crawler itself. Negator disables Spells and Summoning but items can still be used.

Switch Rikku in and put her in Haste, she now gets more turns than Crawler. If Tidus has Slow, cast it or if he has Stunning Steel, strike Crawler with it. Once Crawler is slowed, this fight is easy. Cast Defensive spells if you want but I don't really suggest it. Use your Electro Marbles first. They will deal 900 damage because of Crawler's weakness to Lightning. Once you've ran out of Electro Marbles, use Lightning Marbles. Lightning Marbles deal 1,500 damage. Ouch!

Strategy 2:

If you want the aid of Lulu's spells and aeons, use 3-4 Grenades to rid of Negator and 1,400 of Crawler's HP. Also, Ouch!

Once Negator is down, use Lulu's Thunder/ra/ga spells or her Fury OD. If Crawler is still standing by this time and prepares Mana Beam, don't worry. You have 3 turns to spare. Use Lu's spells for 2 turns and switch Yuna in and summon Ixion on your third turn. Hopefully, Ixion can kill him. If not, no need to worry. Rinse and repeat.