I cant seem to beat the Elite Four. I can get to Steven and kill all of..

No, No, yes level 40.

Your Pokemon needs to be stronger just keep traning until you can't train no more.
Chimecho does not evolve.
Castform does not evolve.
Loudred evolves to Exploud in level 40.

Train Kyogre to L56, teach it thunder, and ice beam and it can beat the e4 by itself. (keep surf and brick break)

Neither Chemicho or Castform evolve.

Loudred evolves into Exploud at level 40.

Customise a stragety or raise the levels on your pokemon

No Chimicheco doesen't evolve

Castform doesn't evolve

and loudred level 36 38 40.

First of all, go to the Meteor falls and catch a Bagon train it a level to evolve, then to 50 to evolve again. Then use that instead of Castform.

Also, Chimeco doesnt evolve, niether does Castform, But Loudred does. In Level 39 to 42. (somewhere in there)

I suggest Training EVERYONE to level 50 at LEAST.

1: Next time would you provide more information, such as which two pokemon you lose by, the type of your castform's hidden power attack, etcetera. As for your team, there are a lot of things you can do to improve your chances against the Elite Four. Here are some which should help.
Kyogre-get rid of hydro pump and teach ice beam instead
Aggron-delete headbutt, cut and fire blast for flamethrower, dragon claw and surf.
Castform-replace all of its moves with flamethrower, ice beam, water pulse and solarbeam.

2: No

3: No

4: It evolves at level 40

evenith_101 ,you get sharpedo and carvahna on routes 118,119.Where did you get Sootopolis from?!!?I think sharpedo is the same.

Who did you lose to?The lv.58?How did you beat the others?Your pkmn are lower leveled than all of them!Try getting your pkmn to lv.65.Try to use Kyogre the most(just watch out for Steven's Aggron.It knows thunder).Loudred?Unless your trying to teach it a certain move,let it evolve!Teach it fire blast.I did it to mine.Steel stinks against fire!Swampert is a W-A-T-E-R T-Y-P-E!!Heloo??Just get it to lv.63and it should be fine.Dont worry about the Agron and thunder cause Swampert is half ground.

Use your kyogre first and use surf on Stevens Pokemon, all of em!

Sec. keep kyogre out and use surf the whole time on every pokemon, cuz its super effective on steel pokemon, O and also buy some full restores. and some revives, cus when kyogre faints ues ur revive to get him bak then use full restore on him.

This is how I beated the elite four:
I used:

Groudon
My Charizard from my action replay codes, cuz I beated the game over and over that I wanted to try somthin new, so I used a action replay codes to get Charizard to replace Torchick, cuz I got mudkip.
Mewtwo from actoin replay
Vaporeon from action replay
Dragonite from action replay

so that right there is the best pokemon set-up
I even got Mew and Snorlax from the action replay codes,

Take my advice and Buy an Action Replay from Gamestop or
EB Games or your nearest game store.

I hope you beated the elite four by now, cus I'm pretty new to SuperCheats.Com