Acid

Acid Armor

Agility

Acid Armor increases your Pokémon's Defense statistic by an amount equal to its initial value. Thus, the first use of this attack results in double the normal Defense score. The second use results in triple the normal Defense score, while the third use results in quadruple the normal Defense score. Effects are cumulative for a maximum of three uses. Further uses have no effect.

Note that like other statistics, Defense has a maximum value of 999. If a use of this attack would raise your Pokémon's Defense beyond 999, it will instead raise it only to that value. If its Defense has already reached 999, this attack will fail.

Also note that since the attacker's Defense statistic is altered, only protection from Physical attacks, such as Swift and Dig, will be increased. No protection is afforded against damage caused by Special attacks like Psychic and Solarbeam.

For more information on the different kinds of attacks and how damage is determined for each of them, see the Attack Base Explanation.

Grimer series
Vaporeon