yes they are really good depends also on the level there are but they are an awesome team i beat the elite four and Cynthia using those same Pokemon but mine were level 89 i battle with them like crazy to reach that level but they are really good choice
Make sure you have plenty of revives and max potions. For Aaron, fire, flying, and rock moves are effective (Infernape, Togekiss, maybe Toxicroak) For Bertha, Water, Grass, and Ice moves are effective (Floatzel, Probopass) For Flint, water, ground, and rock moves are effective (Floatzel, Probopass) For Lucian, Bug, Ghost, and dark moves are effective (Giratina) For Cynthia: Spiritomb= Infernape, Floatzel Lucario= Infernape, Probopass, Togekiss Garchomp= Floatzel, anyone with dragon moves Milotic= Grass or thunder moves Roserade= Infernape, Togekiss, maybe Toxicroak Togekiss= Probopass, rock or thunder moves. I would recommend taking out toxicroak for maybe a luxray or roserade. anyone with grass or thunder moves.
As long as all of your Pokémon are over level 50, you should be fine. You could probably take on most of the Elite Four with the Giratina and Infernape alone. However the Elite Four is over level 54 in it's Pokémon so it's best to pack as much revives, max revies and max potions as possible to even out the imbalance between your overlevelled Infernape and your underlevelled other Pokemon. Overall, you should do fine with a little planning ahead.
it depends of lvls train hard or do your best
Train your Infernape to 70! Train your Giratina to 60 ! Dont bring Tentacruel , Trust me ! Train your Luxray to 62! Azelf to 60! Garchomp to 60!
get all of youre Pokemon to at least level 60. then get 20 revives and 20 max potions.
Teach your Floatzel Ice Punch to use against Cynthia's Garchomp and Surf to use against her Lucario and Gastrodon.
well empoleon is really useful to kick ass garchomp and infernape is great to use against lucario and luxray is useful against togekiss, dialga is great against milotic infernape is great against roserade giratina is good against spritomb. that's all.
It depends on how well prepared you are. I trained my Infernape and Dialga to level 100, and still failed epicly against the elite for. Try and beat them once. It they can't, train.
honchkrow/staraptor (aaron), infernape/rapidash (aaron), leafeon/roserade/torterra (bertha), empoleon/floatzel (flint), honchkrow/spiritomb (lucian), glaceon/abomasnow (cynthia's garchomp)
impossible
it depends what moves they have
Yes, enter Turnback Cave after you beat Cynthia. Go to the portal; it will not be there. Giratina will be standing there.