When I go to fight the dummies(Plot) I use fire against the water one and it doesn't make a hit at all this goes the same for the other two(I beat the Shadow)

I believe that magma is needed for the water one? Someone correct me if I'm wrong, though. :)

You must use magma, not fire. They are different elements. The dummies will block all elements except their weakness.

[edit] If your pets are too weak (which is unlikely, since even basic stat pets should be able to beat them with the right weapons), try equipping and using items such as Dark Light Potion and Dark Magma Potion (depending on the opponent's weakness). The plot guide in the epidemic forums has a list of some basic weapons and such that should help you.

i used fire on him O.o it worked great

Thanks I was using Fire not Magma, though my sister sent me the weapons she used to beat them with and I couldn't figure why nothing was working.