Can some one give me help on beating an opponents Pokemon team?

what you need to do is get a staraptor that is at least level 70. and heatran which you can find on all pearl,diamond and platinum. (heatran is level 70 when you get him). Giratina which is also a legendary and on all three games. I whould go with a Roserade (donphan's weakness is gr) And if you picked chimchar as your starter i whould go with a gyarados. but if you picked turtwig or piplup i would go with a rapidash. if u picked turtwig you wont be needing Roserade so instead i would get a gyarados as well. now for the last one i whould use a luxray. hope this helped and happy battling! :)