It will become super hard, depending on the level of your pokemon. It is recommended that you use reshiram or zekrom on your team because you can instantly put them in your party, and no matter what pokemon you swap out, zekrom will come out first. Since reshiram will be a couple of levels higher, it will go first. It will almost certainly use blue flare. Then you can kill reshiram with a couple of dragon breaths, and sweep the ready of his team with one fusion bolt a pop, because it will be twice as powerful since blue flare had been used. So yes, put him in your team, because he can sweep n. Hope this helps!