What is the difference between Libero and Protean?

Question

Libero and Protean both convert the ability holder's type to the user's attack. So what is the difference between them and which is better?

Comments

They are the same, except for the names and what Pokemon can have the ability.

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I understood it, thanks.

Answer 1

Libero:

Immediately before using any move (except Struggle), a Pokémon with Libero as its Ability will change its type to be the same type as the move it is using. Libero always causes the user to become a single-type Pokémon.
Because Libero activates prior to executing a move, the user will receive same-type attack bonus on every move it uses (except Struggle) regardless of the move's type and will always hit with the move Toxic.

Protean:

Immediately before using any move (except Struggle), a Pokémon with Protean as its Ability will change its type to be the same type as the move it is using. Protean always causes the user to become a single-type Pokémon.
Because Protean activates prior to executing a move, the user will receive same-type attack bonus on every move it uses (except Struggle) regardless of the move's type, and will always hit with the move Toxic.

Hence, both are same, and have the same mechanics. Also, Protean doesn't exist in Gen 8, and vice versa for Libero, only case would be in National Dex.

Source: Bulbapedia
Hope this helps!