>>714797260
>If the wild Pokémon is Magnemite, Grimer, or Tangela, the Fast Ball has a 4× catch rate modifier; otherwise, it has a 1× modifier.
While it is intended to be more effective against all Pokémon that can flee, due to a glitch, it is only effective against the first three Pokémon in the list of Pokémon that have a 10% chance of fleeing (these three being Magnemite, Grimer, and Tangela). The code was intended to instead check the three tables of Pokémon that have a chance of fleeing (Pokémon that have a 10% chance to flee, Pokémon that have a 50% chance to flee, and Pokémon that always flee).

Later games are just high base speed because regular mons don't flee anymore.