you first need to get to the box, get the crossbow and 5000 to upgrade it.
the next round you will keep moving and making as many crawlers as possible. you should have a bunch of crawlers lead them around while the other guy sets up the shot on you.
we did this with two people first try. monkeys will help if you happen to get them but not needed.
p.s fR3SH is not a beast.