You will start on the lower level of the big wand and have a large area
to work with. When the fight starts, Crocker will be shooting Wish Stars
that follow you. Hopefully by this you point you have upgraded Danny
Phantom's Ghostly Wail to the highest level, as it is the most effective
against Crocker.
If you are playing with another player, have them use
Timmy Turner because of his long range attack. However, make sure that
you are always pointing at Crocker or you will lock onto the energy
poles. Once you lock on to Crocker with Danny, he stays locked on as
long as you keep the attack held. It is also helpful to have another
player there to keep the Grunts off your back. After you drain Crocker's
health, use Timmy's Freeze Glove to freeze an energy pole and use Danny
to punch it.
If you are fast, you may be able to get two. When you
destroy the four poles, you will go up a level and must destroy four
more. By this time, Crocker will start using the energy draining Wand
Bombs and the Toy Bomb which turns you into a Grunt if you are hit. The
last level is smaller than the first two, and the energy poles are
harder to reach.