What it does
Acid Armor raises the user's Defense by 2 stages — that's the equivalent of halving all incoming physical damage in one move. It does nothing else: no attack, no secondary effect, just a sharp Defense boost. For a Pokémon with poor physical bulk, that jump from 'easily KO'd by physical hits' to 'requires a special attacker to break' is a real shift in how your opponent has to play against it.
Who runs it
Goodra (16% usage) is the Champions carrier for Acid Armor. Its stat spread leans heavily into Special Defense, leaving its physical Defense notably weaker. After one Acid Armor, that gap closes — physical attackers suddenly find themselves doing far less than expected, and opponents who came in expecting to punch through Goodra physically now need a special attacker to handle it. The setup is worth it when your opponent's damage plan is primarily physical.
How to use it
In doubles, you need a safe turn to set up. Using Acid Armor on turn one while both opposing Pokémon are live is risky — you give up an attack and sit through a hit. The cleaner approach: have a partner use Fake Out to freeze one threat for the turn, giving you a mostly-free setup window. Or set up after your partner has already removed or weakened the biggest physical threat.
Once at +2 Defense, Goodra shifts into a grinding role: stall with Leftovers recovery, let the opponent exhaust their physical options, and convert the board advantage into wins.
Tips & strategy
Acid Armor only pays off against physical-heavy compositions. If your opponent's main damage dealers are special attackers, the boost does nothing — you spent a turn not attacking and they just ignore the Defense change. Check team preview: if you see mostly physical threats and no prominent special attacker to follow up, that's when the setup is worth committing to.
Also keep in mind that Defense boosts don't block passive damage like poison, weather, or entry hazards. If your opponent adapts by switching to a poison or sandstorm strategy, your survival plan needs adjustment beyond just the Defense stat.