approved by macle
Training your Pokemon is a vital part of any game. Of course, that's not to say it's necessary - you can get through the whole game just by battling the compulsory trainers and avoiding as much as you can. It'll be extremely difficult though. Training your Pokemon in the tall grass, caves or water takes up a considerable amount of time, but it's worth it to get through the game with ease and that sense of pride you get. Probably, and most importantly the time you spend levelling up can be made back when you race through the rest of the game, and you go through less difficulty as a result. This is especially important to Nuzlocke players who do not want to see their beloved friends die in battle. This guide is specifically for Ruby, Sapphire and Emerald and gives you a few pointers on where to train and what to look out for.
The first route in the game. This is where you'll encounter your Starter Pokemon and the beginning of your adventure. Incidentally, you will have to pass back through here to get to Odale Town and eventually your Rival. However, you and your Rival will both be at Level 5. And despite their type advantage, you both only have a Normal-type attack in either Scratch, Tackle or Pound, depending on who you chose. As a result, the entire battle is mostly down to whoever rolls higher on the damage rolls and whoever wastes more time using their Atk/Def lowering move of choice. So why waste your time when you can just take them down in two hits by being over-levelled? Let's train!
The great thing about this route is that it contains Poochyena and Zigzagoon, who give 1 Atk and Spe EV respectively. While these EVs may not necessarily take place instantly, they'll give you at least some semblance of an advantage. Wurmple gives 1 HP EV, and whether or not you want those is your discretion. The best thing is that it contains 4 patches of grass, and is near your home and Odale Town - two places for quick recovery. The reason 4 patches of grass is good is because the optimal level you should be before battling your Rival for the first time is 9. Do the maths - 9-5 = 4 levels, 4 levels / 4 patches = 1 level per patch. Of course, this is completely unnecessary, but some people may have OCD.
After good father-child conversation and helping Wally catch his elusive Ralts, this is the next Route you'll come onto. And it is definitely quite a Route. You'll be able to catch Taillow and Wingull from just walking in the very first patch you'll see - your first Fliers, who won't be particularly useful until you reach Brawly (unless you catch Wingull who can use Water Gun versus Roxanne). If you're playing Emerald, Marill is also up for grabs. The things you will want to train for here are the Rich Boy and the Lady. They both have a Level 7 Zigzagoon, and while that doesn't sound like much, you cannot OHKO these guys unless you have super-grinded up until now. Most likely you'll scrape the 2HKO on them, but they have Full Restores, which are annoying. As well as this, there's the Team Aqua/Magma Grunt who will battle you in Petalburg woods, but that's a poor training place since all that appears there is Wurmple, the Cocoons and the odd Shroomish.
The two places shown are by far the most effective, since the first patch is abundant in Taillow and Zigzagoon, who give 1 Spe EV and Poochyena, who give 1 Atk EV. The second spot has plenty of Wingull and Poochyena, as well as tons of hidden items on the ground. Again, avoid the Wurmple unless you're desperate. Marill gives 2 HP if you're training in HP, but they're somewhat hard to find. There is however, a Fisherman on the lower shore who has 3 Magikarps, giving 1 Spe EV each. They're all level 6 so they can't even Tackle you either.
By this point you should have beaten Brawly. If not, then Petalburg Forest is a decent place to train your Flying-type/Torchic until it learns Gust (or Peck, in Torchic's case). But moving on, you should have delivered the goods to Capt. Stern and battled two Aqua/Magma grunts. They won't be too hard, but as you advance north, you will eventually face your Rival, who will pose a challenge. On this route is the Trick House, which updates whenever you earn a badge, so you will be able to run through once and sweep the 3-4 trainers in there for extra experience. There are also a few trainers to the West if you still want EXP points.
In terms of wild Pokemon, this route is full of Electric- and Poison-types. You've got Electrike, Plusle, and Minun, as well as Gulpin and Oddish. Electric-types will give off 1 Spe EV, as well as the Zigzagoon and Wingull you can find here. Gulpin gives 1 HP, and Oddish gives 1 SpA. Emerald players can also come across Poochyena for more Atk EVs. By now, since your starter Pokemon should have evolved (your Rival's starter has), now would be a good time to go killing Oddish to start powering up your STAB moves as opposed to Tackle or Scratch (if you chose Torchic, then Fighting is a STAB that works off Atk, and the preferred one too, since you'll be facing Marshtomp, so that's okay). Interestingly enough, on this route you can catch something to deal with your opponent's starter. If they have Treecko or Torchic, Wingull will make light work. If they have Mudkip, then Oddish fares well.
Route 117 & Route 111
It's worth mentioning you are going to want to train to a decent level on these places before going to fight Wally and then taking on the Gym, since the Gym is going to be naturally hard for those who chose Treecko/Mudkip (unless your Mudkip evolved), due to type matchups, so being at a high level is going to be advantageous.
Take the western exit of Mauville City and you'll find yourself on Route 117. Route 117 is one of the most important routes in the game, quite easily. Why? Well, its one of the few places you can catch Corphish, it has the longest, unblocked straight paths in the game (for egg hatching), and it has two of the most EXP-friendly trainers. Pokemon Breeders Lydia and Isaac both have 6 Pokemon, all at Level 12, meaning they should be a cakewalk for you to plough through, but because they're in abundance, they're good EXP. Plus, these two will ask for your PokeNav number, so you can call them for rematches, when they'll have higher-levelled Pokemon. The grass patches offer nothing amazing, just Zigzagoon, Roselia, Oddish and one of the two firefly Pokemon (Illumise or Volbeat). However, Roselia and Oddish both give off 1 SpA EV, so they can be useful.
Backtracking up to Route 111, you won't go very far due to the Rock Smash rocks in your way but before that, there are one or two trainer battles that may catch your eye. If you're playing Emerald, there are a few double-battles here and there that may catch your attention for raw exp, but these will be walk-overs. The real draw is the Winstrate House. Not only will you get a Macho Brace for beating these guys, but their Pokemon are pretty buffed. I would say they're a match for the Gym's trainers! Since you will face all 4 of them in succession, I suggest putting your lower-levelled Pokemon first, or one you want to EV train in Speed, because starting off, Winstrate Victor has Taillow and Zigzagoon, both giving 1 Speed EV, both at Level 16. He's followed by his wife, who has a Level 17 Roselia (1 SpA), then their daughter, who has Marill, Shroomish and Numel, all at 15. Marill gives off 2 HP, Shroomish 1 HP and Numel 1 SpA. The last Winstrate has a Level 18 Meditite. These guys are great for gaining EXP, so take advantage of it. Past this, most of the game is just Trainer battles. Hit up the Interviewer Gabby and Ty though, since they're constantly re-playable and worth nice EXP.
Route 114, Meteor Falls, and Route 115
Route 114 isn't interesting. The only reason it's worth mentioning is because you can encounter Magikarp and Goldeen, which give 1 Spe and 1 Atk EV respectively. This is also pretty good in that they're both extremely weak, making grinding for EVs simple. However, if you thirst for raw EXP, then the Solrocks you find in Meteor Falls are pretty chunky and good fun to take down. Route 115's Trainers are full of Fighting-types, and they're all worth getting into a scuffle with. At this point in the game, most of your EXP will come from Trainer battles, since Wild Pokemon are going to be extremely weak. However, the change in difficulty once you get to Lavaridge town is much higher. There isn't a lot you can do - the levels of Trainer Pokemon hop into the low-mid 20's. The best thing to do is use the Gym Trainers to boost the strength of your anti-Fire-type. Usually, that's Water or Rock at this stage, both of whom should have received sufficient training through Fiery Path.
Sadly now, you have to go back to Petalburg, and the massive problem is that there's nothing between Lavaridge and Petalburg that is worth training against, so once again, you go from one Gym to another with nearly no extra training.
Route 119 and 120
These routes are beautiful; not least because they're not only teeming with wildlife, but the wildlife is of reasonable power - Pokemon range from Level 23 to Level 27. They'll be roughly equal to the level of the Petalburg Gym trainers, giving you an idea situation before heading into Fortree Gym. In both routes, the likes of Linoone, Oddish, or Mightyena can appear, all of which are pretty handy for one thing or another. Absol is rare but definitely worth taking down in Route 120. Sadly the trainers on Route 119 are nothing special, bar the dude with the Breloom and the kid with a Ninjask. Oddish and Linoone are the standard encounters, with Tropius appearing here and there. The EXP yield on Tropius is pretty meaty, but their low appearance rate isn't worth waddling around the grass for - you'll kill plenty of Linoone and Oddish in the meantime anyway.
However, what Route 119 does hold interesting is the Weather Institute (as well as a Rival battle). The Team Aqua/Magma grunts should pose zero problem, but the Admins inside hold two level 28s, which is good for training up lower-levelled Pokemon.
In Route 120, if you fought them back in Route 111, Gabby and Ty will be standing around. Some nice bonus there, especially since Winona's Pokemon are in the mid-30's. Back down in Route 120, once you get past Steven and the Kecleon, there are some nice Trainer battles to get caught up in before you go for the Gym. In R/S, you can be up against a Castform and Milotic (in two separate battles). Emerald pitches you in a double battle against a Sableye and Manectric. Evolved Pokemon are always nice for high EXP gain. At this point, you'll be good for fighting the Gym. Next, Route 122 and Mt Pyre are some fun spots to explore.