Regular stuff
Longest pokemon that isn't fully evolved (onix)
First non-legendary to be a major part of a movie
Prior to gen 4, this ghost type hit the hardest with its STAB moves
This pokemon has the lowest bst of any cross-gen evolved form introduced in Sinnoh
This pokemon hasn't been featured in a Who's that Pokemon? (prior to Pokemon Journeys)
Only legend/mythical with a 4x steel weakness (diancie)
This Alola pokemon's STAB combination is super effective against 9 types
Only pokemon from Galar (as far as I know) to be mentioned in a dex entry for a Kanto pokemon (copperajah)
Non legendary/paradox/dlc Paldean pokemon with the strongest signature move (not counting moves that get stronger like Kowtow Cleave or multi-hit moves)
Moves and competitive stuff
This is the only fighting move that Mawile resists (flying press)
This pokemon is the reason why Smogon's AG tier exists (Mega Rayquaza)
Only Kanto pokemon to never be below OU tier
Only attacking move prior to Gen 9 dlc that could badly poison (Poison Fang)
In the TCG this pokemon could evolve directly from a basic to a stage 2, skipping over its stage 1 evolution
First mainline box art legend to be banned from Smogon's uber tier (mega rayquaza again)
Only ghost move that can miss (poltergeist)
First rock attack with 100% accuracy (ancient power)
Only attack that can infatuate opponents (GMax cuddle)