Gen 4 Additions
The battle system was changed to designate damage types on a move by move basis instead of by typing after this change.
Physical-Special Split
Arcanine, Electrode, Lilligant, Goodra
Pokemon that added a type in their Hisuian form
This Pokemon generates an extra Pokemon in the party upon evolution.
Nincada
This metagame allows all abilities to be selected for Pokemon except for a few bans.
Almost Any Ability
This Pokemon is Bug/Steel and is often used for both hazard stacking and removal.
Forretress
This item was introduced to seek out wild Pokemon in tall grass, mostly used for Shiny hunting or to find exclusive Pokemon in an area.
Zubat, Geodude, Paras, Clefairy
Pokemon found at Mt. Moon (FRLG)
This Pokemon evolves into different forms of the same species depending on which game the player is playing.
Rockruff
This metagame has Pokemon using all of their native abilities at once.
Pokebilities
This Pokemon changes typing with weather.
Castform
This trading system was implemented to allow players to trade Pokemon with online players anywhere in the world.
Global Trading System (GTS)
High Jump Kick, Soft-Boiled, Vise Grip, Feint Attack
Moves with name changes
This Pokemon's personality value determines which evolution branch is chosen.
Wurmple
This metagame is a double battle where all moves and abilities are shared between allies.
Partners in Crime
This Pokemon has the lowest evolution level for all final stage starter Pokemon.
Power items
Caterpie, Larvitar, Wurmple, Weedle
Pokemon that lose a HA upon evolving then later regain one upon evolving again
This Pokemon's evolution is entirely dependent on gender, splitting into 2 different species.
Burmy
This metagame turns every attack into a pivot move.
VoltTurn Mayhem
This Pokemon reads the the same forwards and backwards, just like its pre-evo.
Farigiraf
These 4 side game series received new entries in Gen 4.
Hariyama, Vespiquen, Garbodor, Trevenant
474 BST
This Pokemon splits into multiple evolution branches including both 2-stage and 3-stage evolutions.
Applin or Mime Jr.
This metagame allows a move to replace the item slot, granting said move's primary and secondary effects to the rest of the Pokemon's moveset.
Fortemons
This Pokemon has two forms, where the applicable form here is slightly heavier, as an extra family member is added.
Maushold-Four