mlarox

If your at the place where you battle the three legendaries (suicune, entei, raikou), then what I do is get Pokemon that maximum poke assist and get the following types:
Suicune- you can use plusle/minun, just make sure that their energy is at maximum
Raikou- try using a ground-type Pokemon, like golem
Entei- use water, like feraligatr.
Its pretty hard to time it just right, but just try to avoid his attacks. I wouldnt even try to capture him unless hes in a bubble or something. And when you do, make sure that there is no fire or anything that can harm you on the screen. Hope this helped!