Ok I was playing on my ds and I found the ultimate double battle pokemon for 3 gen that arnt legendary they are latios (if you can call him nonlegendary the battle frontier doesnt or use dragonite) and lapras.

this is why

lapras's special ability lets it take surf and makes it its own hp and surf hits both enemies and give him shell bell and hes unbeatable
latios can learn surf pyshic icebeam and thunderbolt and give him leftovers and its even harder to beat

using this strategy I have done 100 battles in the battle frontier in a row

Think you can beat it? please tell me your team!