RE5 help please-- last boss

my cousin have beaten all of RE5 in one sitting, and we are stuck on the last boss. here are the problems.

he is sheva, once his second arm goes buff and stuff, he jumps over to her side. she tries to jump the bridge, but fails EVERY time.

i have no idea what to do just sitting over there. i have no sniper. and theres no way for me to keep him on my side to do extra damage.

help please! he's leaving sometime this morning and we need to beat it!

I played that part solo so i was Chris but you just have to shoot him and Wesker will start throwing boulders at you. Your cousin should be given a QTE that takes a while to complete.

shoot him with anything (even a shotgun can trigger him)when sheva is trying to climb, he'll start throwing stuff at you...when she succeeds, push the boulder...