Entrainement Pokémon

To make a Pokémon stronger, you have to train it in battle and gain experience.

Universal

• When training a Pokémon, it is best to be near a healer, as the Pokémon in training will eventually be worn down by the large number of Pokémon it is fighting, HP or PP-wise. Both a Pokémon Center's healers or a crafted healer that is placed in a convenient spot will work. Keep in mind that a healer cannot be retrieved once placed, and breaking it with a pickaxe will only give back an aluminum plate.
• Two held items, the Exp. Share and the Lucky Egg, both help with experience gain. They can be obtained as drops from boss Pokémon or from PokéLoot chests.
  • An Exp. Share gives the holder 50% of the experience before distributing any remaining experience normally. This means that if the holder enters battle, it will gain more of the total experience than usual. Note that an Exp. Share doesn't increase the total experience gained at all.
  • A Lucky Egg increases the amount of experience gained by the holder by 50%.
• Each species of Pokémon has a different experience yield. This factor is relative to other Pokémon, not a flat number. Generally, evolved Pokémon have a higher experience yield than unevolved Pokémon.
• An opponent of a higher level will give more experience than a lower-leveled Pokémon of the same species.
• A lower-leveled Pokémon will gain more experience than a higher-leveled Pokémon in the same situation.
• Not all Pokémon require the same amount of experience to level up.
• The maximum level a Pokémon can reach is level 100. Boss Pokémon are an exception and may exceed that level (up to level 140 under certain circumstances), but they cannot be captured.

Training weaker Pokémon

• A weaker Pokémon, like a newly-caught Pokémon or a starter Pokémon, is not usually ready to battle Pokémon that are of a higher level than they are. Despite type advantages, many Pokémon do not initially have moves of their type, instead having only a weak Normal-type move like Tackle or Scratch. They should typically only engage in battle with Pokémon that are of their level or lower.
• At very low levels, Magikarp that are level 14 and under are exceptions, as they only have the non-damaging move Splash, allowing any Pokémon to chip away at their health. They are also very common in most bodies of water. However, this only applies to very low levels that can take advantage of the level difference, as Magikarp have some of the lowest experience yields compared to other Pokémon of their level.
• If you have stronger Pokémon available as well, it is possible to use the "bait-and-switch" method. To do this, send out the weaker Pokémon against any foe and immediately switch it for a stronger Pokémon. The weaker Pokémon will gain half of the given experience against a foe that it normally cannot beat. An Exp. Share can be used in tandem with this method to increase the experience gain of the weaker Pokémon to 75% of the total experience.

Training stronger Pokémon

• Higher-leveled Pokémon can start using their type advantages and stronger moves to defeat wild Pokémon that are somewhat higher-leveled than them, as well as more reliably defeating Pokémon around their level as long as they deal neutral damage to their opponents. In particular, boss Pokémon give relatively large amounts of experience due to always being at higher levels than your Pokémon, along with providing several useful drops like held items and TMs.
• As certain biomes predominately contain Pokémon of specific types, it is possible to exploit super-effective matchups against the dominant type of the biome to defeat Pokémon faster and more efficiently. For example, Rivers and Oceans have mostly Water-type Pokémon, Deserts have mainly Ground and Fire-type Pokémon, and Jungles have a lot of Bug and Grass-type Pokémon.

Multiplayer

• Note: Gaining experience in player-vs-player battles can be disabled in the Pixelmon config file by setting "allowPVPExperience" to false. Be aware of this possibility before using the methods below.
• As Pokémon gain experience even in player-vs-player battles, the process of training can be easier if you have a willing partner with Pokémon that are of decent or high levels. Simply stand next to a healer, start a battle, have your partner's Pokémon use status moves or switch out constantly (actions that don't hurt your Pokémon), defeat your partner's Pokémon, have your partner heal his Pokémon, and repeat until your levels are satisfactory. This process can easily been done in reverse as well.
• Blissey has by far the highest experience yield among Pokémon. One player can obtain a Blissey, level it up to a high level, and allow other players to constantly defeat it to gain a large amount of experience each time. If the owner of the Blissey wants to train their own Pokémon, the Blissey can be traded to another player and repeat the process.

Commands

• If allowed, commands make training completely unnecessary as it is possible to give yourself a level 100 Pokémon with /pokegive, albeit with four random moves from its level-up movepool. If level-up moves are desired, a move relearner can be used.

EV training

• Besides by leveling up, Pokémon can also become stronger by gaining EVs. Details on how to take advantage of this mechanic can be found on this page.