the best way is to take at least 5 thunder and dark for the rest ; let him come to you and....go for it !!!!

Get three light and six fire don't wait for him to come go after him

get stronger monsters

u jus have to get really strong monsters and they have to be wat ever ur symbol is and maybe 2 of them have to be thunder. A good tip is to power up strong monsters w/ the same attribute as ur symbol and then use them to beat kaiba. the best symbol 2 get is dark.also LET KAIBA COME 2 U!! i have used this strategy in all of my matches and have beaten this game 4 or 5 times w/o losing a single duel...it really is the best strategy...but u also have to power up a good variety of monsters but the ones w/ the same attribute as ur symbol have to be the MOST powered up! :)