Ability₁₃₅-Magnet Pull

Magnet Pull prevents adjacent Steel-type opponents from fleeing (including Teleport) or switching out as long as the user remains in battle.
⚠️However, if a Pokémon with Magnet Pull switches in, Steel-type opponents that decided to switch out at the beginning of that turn but have not yet moved will still switch out.
⚠️Using Baton Pass, U-turn, Volt Switch, Flip Turn, or Parting Shot will still cause the Pokémon to switch out.
⚠️Holding a Shed Shell allows the Pokémon to switch out, but not flee or use Teleport.
⚠️Having the Ability Run Away or holding a Smoke Ball allows the Pokémon to flee or use Teleport, but not switch.
⚠️If a wild Pokémon has Magnet Pull and the player's Steel-type Pokémon faints, if the player attempts to flee instead of sending out another Pokémon, they are unaffected by Magnet Pull.
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💥In Battle💥
🟢Gen³ Magnet Pull affects allies.
🟣Gen⁴⁺ Magnet Pull no longer affects allies.
🔵Gen⁵⁺ Steel-type Pokémon are now unaffected by Magnet Pull if they have Ghost as another type.
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🛤️Outside Of Battle🛤️
From Pokémon Emerald onwards, if a Pokémon with Magnet Pull is in the first place in the party (even if fainted), then there is a 50% chance the game will force an encounter with a Steel-type Pokémon, if one is possible.
🔵Gen⁸
In Pokémon Sword and Shield only, the chance is 51% instead.
🟣Gen⁹
In Pokémon Scarlet and Violet, this Ability has no effect outside of battle, with its former field function effectively being replaced by Meal Powers.
~Bulbapedia