Pelican Island is the second stage in Sub-chapter 17, Alcatraz.
If you have trouble inflicting damage on Master A., it's a sign that you need true form cats.
Master A. has a magnification of 400%. Beware of the peons that support him. Duche and Otta-smack-u mostly are 400%, so they may plow through your lines easily. They lack the "color" type, so Cats against a certain type won't do you any good (except Shadow Gao). Bahamut can't hit the Master A. even once, so don't bring him. If you have Valkyrie Cat's true form, bring her.
Cat Line Up (Important Cats are in Bold Font): Crazed Macho Cat, Crazed Wall Cat, Crazed Brave Cat, Macho Legs Cat, Crazed Sexy Legs, Valkyrie, King Dragon, Crazed Dragon, Jamiera Cat, Crazed Titan Cat, Crazed Whale Cat.
Try to take out the Otta-smack-u's and Duches as fast as you can. Once no peons are in your way, fire the Cat Cannon and spam the bold-fonted Cats listed above. Rinse and repeat.