Well first off, you definately need to level up more. None of your pokemon should be below the level 40-45 range if you want a bare minimal chance of survival against the elite four.
Like ShinyManafi said, get rid of Beautifly and Linoone, their stats are just to low to do your team any good. You WILL need a good water pokemon with surf/ice beam, I reccomend evolving your Lombre and teaching it those moves.
EDIT: Your post beat mine, so keep Linoone.
If you need a pokemon to beat Phoebe, get a normal type with shadow ball, (i.e. Slaking, Exploud, ect.) since they would be immune to ghost moves, and be able to land a super effective hit with shadow ball.
Or you could keep Mightyena and teach it howl and shadow ball, since it has decent attack and ghost moves aren't very effective against it.
And a thunderbolter or fighting type wouldn't be a bad idea, especially if you're playing emerald, where having an electric attack/pokemon is EXTREMELY helpful.
I would get rid of all the HM moves, save surf, since they're not very useful in battle and waste a move space. Also, try not to use two moves of the same type, it really limits the types you can cover. Maybe replace Gardevour's confusion with thunderbolt, Lombre's dive/waterfall with ice beam, and one of Sceptile's attacks (But NOT leaf blade) with Dragon Claw or something. (That's if you don't mind using the TM, just that Sceptile doesn't have very many move options unless you can breed, where you can get crunch on it)
Mightyena isn't too good either, I would reccomend getting a good ground type such as Donphan or Rhydon, or maybe a good normal type, like Slaking or Dodrio even. (Though if you need it for Phoebe, then keep it)
Then, just level them up a lot, so that they're in their forties. Then when you go to battle the Elite Four again, make sure you bring a lot of hyper/max potions, full heals/restores, and revives to heal your pokemon if you need to.
And one more thing, can you please tell us which game you're playing?
~Aquarelle
