HM slaves
There's no getting around it - you're going to need to use the skills taught by Hidden Machines (HMs) in order to progress anywhere in this game. There are exits blocked by smashable rocks and foliage that needs cutting, rivers and oceans to be Surfed upon, and hills and waterfalls that need to be scaled.
The problem is that an HM skill takes up one of a pokemon's four skill slots. Since you've only got four per poke, all of the slots are very valuable, and you'll want to make sure each one has a useful in-battle skill in it. Most of the HM skills, however, are pretty crappy in combat. Rock Smash might be able to clear away some boulders, but compared to other Fighting-type moves that become available as the game progresses, it's quite weak. There are even some non-HM skills like Flash that are useful outside of combat, but pretty worthless otherwise.
Making things worse is that there's only one way to delete HM skills from a pokemon's skill set, and that's through the Move Deleter in Canalave, who you don't meet for a while. Has your poke leveled up and wants to learn a new skill? You aren't going to be able to dump the HM skill, so you're stuck eliminating one of the others. This is particularly bad when an HM move is clearly the worst of your pokemon's moveset, and you're forced to either overwrite a useful skill or forget the new skill altogether.
There is, however, a pretty effective way of getting around this problem. Take a pokemon that you don't plan to use in combat much (if at all) and load it up with HM skills, then bring it with you in areas where you'll be needing HM skills to proceed. While this solution forces you to commit one of your six team slots to the "HM slave" when you're exploring, it allows your other, stronger pokemon to build and utilize their individual skill sets to their fullest.
Above: The Bibarel. This chubby bastard won't help you in battle, but use him and abuse him for all your HM desires
Since certain HMs are only usable by certain Pokemon, which ones make the best beasts of burden for HM use overall? We recommend using Bibarels - they're quite common from about mid-game onwards, and they are able to learn 6 different HM skills that are necessary to finish the game: Cut, Surf, Strength, Rock Smash, Waterfall, and Rock Climb. Most of the common flying-type pokes (Hoothoot, Starly, Zubat) can use both Fly and Defog - skills that aren't a complete necessity, but nonetheless are extremely useful in many places. Usually you'll only need to have one HM slave with a few essential skills to get through most obstacle-laden areas, but in some places (like Victory Road) you'll need almost all the HM skills to proceed. In those cases, you'll either have to bring along an extra HM slave or bite the bullet and put an HM or two on one of your main pokemon. (Thankfully, by the time you have all 6 essential HMs, you'll have ready access to the Move Deleter, so you can replace the HMs later. It's just a bit more of a hassle.)
If you simply must stick on HM on one of your primary pokemon, we recommend it be Surf, which is actually a pretty strong Water-type attack. In fact, once you're able to use it, it's a good idea to have a Surf-capable poke on your person at all times.
Above: The Bibarel.This chubby bastardwon't help you in battle, butuse him and abusehim for all yourHMdesires
Since certain HMs are only usable by certain Pokemon, which ones make the best beasts of burden for HM use overall? We recommend using Bibarels - they're quite common from about mid-game onwards, and they are able to learn 6 different HM skills that are necessary to finish the game: Cut, Surf, Strength, Rock Smash, Waterfall, and Rock Climb. Most of the common flying-type pokes (Hoothoot, Starly, Zubat) can use both Fly and Defog - skills that aren't a complete necessity, but nonetheless are extremely useful in many places. Usually you'll only need to have one HM slave with a few essential skills to get through most obstacle-laden areas, but in some places (like Victory Road) you'll need almost all the HM skills to proceed. In those cases, you'll either have to bring along an extra HM slave or bite the bullet and put an HM or two on one of your main pokemon. (Thankfully, by the time you have all 6 essential HMs, you'll have ready access to the Move Deleter, so you can replace the HMs later. It's just a bit more of a hassle.)
If you simply must stick on HM on one of your primary pokemon, we recommend it be Surf, which is actually a pretty strong Water-type attack. In fact, once you're able to use it, it's a good idea to have a Surf-capable poke on your person at all times.
