May I make a suggestion?
I found the best way to deal with emerald.
Pokes will be gotten: Blaziken, Golduck, Vileplume, Giraffarig, Rayquaza)
If you think there is a chance that you ight lose, save. If you lose, restart. That way, you wont lose money and eventually win.
If your pokes lvl does not match with the guide, don't worry. I am mimicing my game and t was easy to get through, but hard to remember. As long as yu do not lose oftenly, (losing once in every 50 trainer or so or losing in gym leaders are OK, but more are a problem) you're OK. Oh and dont use tms and tutors unless stated to do the opposite
Train no other pokes than stated above and never waste your rare candies unless told so and try not to buy anything because you will never lose. Then you will almost never have to train outside battle.
First, you WILL have to train outside in the start but only the start. Get your torchic to lv 16 and teach it peck and double kick before getting the first badge. Battle and win. Might need some luck, but it is easy if you have some handy potions.
Go to the island and get the letter before beating te gym. (Go and catch an oddish in the route near slateport and train it. I don't remember if you had to fight team magma there to get to the route but if you have to, dont fight them. They are all exp for the oddish.) Beat brawly, now you should have your combusken like 20-25 by now. Train oddish now in battles. It will be enough to get it to 25.
When all are 25, battle the electric gym and use fire moves. I you have enough money, go and buy a flamethroer tm. By now your poke should have the following attacks.
Combusken:
-DoubleKick
-Ember/Flamethrower
-FocusEergy
-HM Move
Gloom
-Acid
-Arbsorb
-BulletSeed
-...Powder
Get some hm slaves, and get on your way. The two should grow near lv 30-35. Try evolving you combusken first since it will need attack power to deal with torkoal. Flanerry gym will be hard, but to cover the fire weakness, you will catch a golduck.
Normna is waaaaay easy with blaziken.
By the time you reach winona, you should try to get your pokes to lv 40. (And you wil on the way to safari zone, dont worry. Try to avoid trainers or you will steal exp from golduck) Dont battle winona, but enter safari zone and catch a giraffarig and a golduck. Try to train golduck to higher levels first because it will be the main icebeamer. Get all your pokes around lv 40. Golduck gets sur, icebeam, confusion and psychup. Giraffarig gets psychic move, stomp, gility and baton pass. This team shoul be perfect for now and you cann freeze winona and burn her skarmory.
You should save blaziken to all team ... grunts and try to raise giraffarig to lv 44. Once it is 44, give it 5 rare candies you find around, if you dont, level up (Sadly) and teach it crunch. That should deal with liza.
Against liza, take golduck and giraffarig. Beam and crunch claydol first, earethquake is devastating. Then kill xatu. Rest is hard, your giraffarig might faint so pull blaziken in the play and kick them. Your main focus should be keeping golduck alive to copy the stat changes that lunatone does and gloom(should be vileplume by now, find a green shard, you can find one near the inner borders of the sea) to bullet seed lunatone.
Rest is easy, go, do the events, catch rayquaza(beam it maybe freze and ultra ball. It is easier to catch whilst flyng note you) Teach rayquaza dragonclaw(for e4 dragon), fly(hm), crunch(4e4 ghost) and thunderbolt (4e4 ice and water). Kill the water gym but train your vileplume and blaziken by defeating the trainers down the ice. Try to kill Juan by vileplume to raise it.
Go to the league. It is a goo idea to train in the trick masters house first. Save before fightig every e4 and before you enter wallaces room. If you don't have any max revives or full restores get them now. Give rayquaza the amulet coin. Your vileplume should know petal dance by now and you shouldve kept double kick by now. Defeat dark e4 with blaziken (rays thunderbolt to crawdaunt). e4 with crunch better if you use fly on the first dusclops because it will use protect two times the start. Fry glailes and zap walrein and its pre-evos. Claw the dragons and zap the waters. Beware of milotic, it will have hp left after you attack it and constantly us efull restore. I suggest you to do the same if it takes more than half of your HP. Defeat ludicolo with vileplumes acid and defeat whiscast with a single petal dance. You finished the game! And you are filthy rich!
And yes, do you have the Giga Drain Tm with you? When Sceptile's HP starts running low, it would be a good idea to have that along with you.