What moves do they have and what are their stats ? I see you got a Flying/Dragon, Pyschic, Grass, Normal, Dragon/Ground . I beaten them before and I guess they'll take down Gardevoir, Flygon, and Sceptile easily .
They have moves that are not predictable, unless you battled them like a couple of times . Rayquaza has lot's of power which can take down all the elite four, you should give Crawdaunt an ice type attack before battling the champion and Delcatty attract and sing, which can take down a tough opponent .
Rayquaza sweeps Emerald's Elite Four. Trust me, I've been there before. All you need to do is have Rayquaza learn Ice Beam and Thunderbolt. Just be wary of Wallace's Milotic.
Of course Milotic! Most exhilarating 20 mins of my Emerald... Last Pokemon vs Wallace's last Pokemon... Milotic vs. Milotic... It took a loongg time to win the battle.
Yup, 20 minutes. Recover and Recover again and again. And I'm quite determined to prove that my Emerald version's Milotic is stronger than his... (Sadly, my Emerald got deleted after I beat the Elite Four.)