Make sure you don't use big words
keep your rhyme schemes simple
avoid any form of lyricism other than puns and similes.
Make sure all your puns and similes pertain to sports, pop culture or similar things.
Make sure to pretend to be a gangsta and talk like one, doing your best to sound like a neanderthal who has never read a book.
Keep in mind that battles are not won through skill, they are won by being with the "in crowd" and appealing to the stupidity of the majority of users.