How do you beat the elite 4 and the champion?

This a pretty vague question, but I'll answer in the way that I know how to. To beat the Elite 4 and the champion, first you need to beat the Elite 4 and then N and Ghetsis. After you've done this, you can return to the Elite 4 and battle them again in order to beat Alder, the Champion.

That is only partialy correct, you must first go to the top of the Pokemon tower and speak with Alder before you can challenge him to a battle at the Pokemon leauge.

Use following strategy: all pokes at least lv.75,use the pokes that are strong against the 4 along with moves.have a lot of max revives,revives, or revival herbs. Revival herbs acan be caught near cold storage. Psych is the hardest so beat her first (top right) then dark (bottom left) then the rest. Hope I helped! }:-)

Use following strategy: all pokes at least lv.75,use the pokes that are strong against the 4 along with moves.have a lot of max revives,revives, or revival herbs. Revival herbs acan be caught near cold storage. Psych is the hardest so beat her first (top right) then dark (bottom left) then the rest. Hope I helped! }:-)

Get your Pokemon to at least level 80 then go to the Pokemon league and beat elite 4 then N and ghetsis then go in the cave where you came from and Cheren will be standing there it will be called the final battle

All of the top answerers...SHUT UP!!! You need to defeat all of the gym leaders first. Second, defeat Pokemon league the first time. Tip:The Pokemon league's Pokemon will be at LVs 48 to 50 so have your Pokemon at least LV 56. Then beat N and Ghetsis. Train your Pokemon to LV.82 and take on the elite four again then battle Alder. PS.If you want a real challenge then go to Undella town after main story and face of against sinnoh's champion!
PSS. Rematches only available in the spring once a day.

The Elite Four is easy so I will help you.
First stock up on full restores,Revival herbs,Max potions and full heals.
Okay I will tell you the Elite four's name and the type they use
1-Marshal-uses fighting type so use a flying or psychic type.
2-Caitlin-uses of Psychic type so use a dark or ghost type.
3-Shauntal-uses of ghost type so use a dark type ONLY because a ghost type is super effective against another ghost type
4-Grimsley-uses Dark type so use fighting type AND becareful of using Fighting type because his Purrloin knows Ariel Ace
Champion-Aldar-uses fire type but be careful because his Accelgor tend to use energy ball and use a fighting type at the end because he sends out a Vanilluxe
Hope this helps

You need a a level 85 or higher get a lot of revives so you can live please tell me if this helps

You have to beat the main story line then make your Pokemon are at least lvl 85 and battle alder