The Gym Leaders are not the Only People to get an enhancement in the game. The Elite 4 Have been given new Pokemon at New Levels and there is also a New Champion:

Updated Elite 4 Sets in Emerald

Elite Four Sidney Mightyena Absol Shiftry Cacturne Crawdaunt
Lv. 46 Lv. 49 Lv. 48 Lv. 46 Lv. 48

Elite Four Pheobe Dusclops Dusclops Banette Sableye Banette
Lv. 48 Lv. 51 Lv. 49 Lv. 50 Lv. 49

Elite Four Glacia Sealeo Sealeo Walrein Glalie Glalie
Lv. 50 Lv. 52 Lv. 53 Lv. 50 Lv. 52

Elite Four Drake Shelgon Flygon Altaria Salamence Kingdra
Lv. 52 Lv. 53 Lv. 54 Lv. 55 Lv. 53

Champion Wallace Wailord Milotic Tentacruel Ludicolo Gyarados Whiscash
Lv. 57 Lv. 58 Lv. 55 Lv. 56 Lv. 56 Lv. 56

 
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