There is no "best" Pokemon to defeat the Elite Four. You can use any Pokemon you want, as long as they are strong enough to face them.
If you want to strategize, Lorelei uses Ice Pokemon, so Fire, Electric, and Grass types would be useful against her. Bruno uses Rock and Fighting types, so Water, Psychic, and Fighting types would be useful against him. Agatha uses Ghost types, so Psychic, Ghost, Bug, and Poison, would be useful against her. Lance uses Dragon types, so Ice would be very useful against him. As for your rival, you'll need a combination, there isn't just one type to defeat him.
Just use a combination of the above types.
After you defeat the elite four on Pokemon sapphire you complete the pokedex and make all your Pokemon level 100.
You go and have a tug
In any Pokemon game, you must defeat the elite four and the champion.
No you must beat the Elite Four first
i think u have to defeat the other gym leaders then find groudon then its the elite four but remember you have to find all the Pokemon after elite four
yes swarpert is a greatest Pokemon to defeat elite four
Wailord
you defeat the elite four by training a particular Pokemon and getting it to a high level(e.g. lv64) you also give it the best four moves that you have. try to give it moves that have a lot of pp though because you need to defeat the elite four who have a lot of Pokemon!
defeat the elite four
After you defeat the elite four on Pokemon sapphire you complete the pokedex and make all your Pokemon level 100.
The best levels to have are 60 or above Pokemon wise i doesn't matter the easiest way to beat the elite four is train Pokemon that defeat each members Pokemon.
The best way to defeat them is to train your Pokemon. No Pokemon will be above level 50 or something like that. The 4 main elite four, their Pokemon are only in their forties.
After you defeat the Elite Four.
Defeat the Champion in the Elite Four.
There is are no certain Pokemon needed to defeat the elite four. Just use your strongest Pokemon.
there is no elite four for kanto u just defeat the elite four that is in kanto for the johto region. and my advice for it is have the Pokemon the elite four Pokemon and the champion Pokemon are weak to like for champion it would be ice.
which elite four are you referring to. use bug and fightning move to defeat dark pokemon.