Terminus Cave – Zygarde's Chamber

Fly to Couriway Town or Anistar City and head to the Terminus Cave. Head to the deepest part of the cave where an NPC is blocking the path before. As soon as you enter, you'll notice that the BGM stops and the whole area falls into silence, with the exception of the sound of water drops.

Head north and you''ll find the central platform where the legendary Pokemon is resting. Before approaching it, there are some items you can get here. From the central platform, head to the southwest to find an Adamant Orb. This item boosts the power of Dragon and Steel-Type moves. To the northwest you'll find the Griseous Orb. This item boosts the power of Dragon and Ghost-type moves.

There's a hidden Big Nugget to the northeast corner and a Lustrous Orb in the southeast. This orb increases the power of Dragon and Water-type moves.

Now make your preparations and head to the central platform. Save your game and approach the legendary Pokemon in the middle.

Before engaging it to battle, you must be prepared:

• SAVE YOUR GAME FIRST.
• Have a powerful, primary Pokemon that has high SP Def and not weak to Dragon, Ground or Dark attacks.
• That Pokemon should have a move that can put a Pokemon to Sleep. Having the capability to use False Swipe is also recommended.
• Bring a lot of Pokeballs, preferably Ultra Balls and Timer Balls.
• Use Capture Power.
• Bring a lot of healing items.
• Have your primary Pokemon hold an item that will help boost its defense or accuracy. Wide Lens is recommended since it will boost the accuracy of your moves; very helpful in helping land more hits, especially Hypnosis.

LV70 Zygarde (Dragon/Ground)

Zygarde has an impressive stat all around but it has better attack and defense ratings. Fortunately, unlike Mewtwo, it doesn't have a healing move like Recover so as long as you reduce its HP to 1 using False Swipe, it will stay there. You'll just have to concentrate in putting it to sleep.

Earthquake is its most powerful move. It deals high damage; twice the damage for Pokemon which used Dig to go underground. It is especially bad news to Pokemon weak against Ground attacks or those with mediocre defense ratings.

Crunch is a move that has 20% chances of lowering the target's defense so watch out for that. If ever the debuff connects, you have to increase your Pokemon's defense again or face the increased damage from Zygarde's other Physical attacks.

Its only status move is Camouflage which changes its type to Rock. However, this can only be used once and any succeeding attempt to use it will just fail, giving you free chances. Do not use moves that will poison or burn it, since Zygarde doesn't have any way of restoring its HP.

If possible, use moves that will increase your own Pokemon's stats, specially its defense and accuracy. Your chances of catching it increases considerably once you got it down to 1 HP (via False Swipe) and while it is sleeping. As the battle takes longer, your Timer Balls will become even more effective as well. Zygarde is very stubborn so be prepared to spend a lot of balls. In my end, I was able to capture it after my 6th Ultra Ball.

As a reference, I'll share the Pokemon I used:

LV92 Gallade (Psychic/Fighting)

Held Item: Wide Lens

Moves:

• Power Up Punch
• False Swipe
• Hypnosis
• Mean Look

Since Gallade is a Psychic/Fighting Pokemon, Zygarde's offensive attacks will just deal normal damage. Gallade also has high SP Def, good Def stat and even higher Atk stats – perfect for boosting physical offensive moves such as False Swipe. I opted using Power Up Punch. Even with this move's 40 base damage, the Atk stat boost it provides after every use is very useful. The high level ensured that I'll be able to deal more damage and endure more damage, particularly against Zygarde's Earthquake. You can even reach LV100 by grinding in the Battle Chateau. You can use other Pokemon of your choice; just remember, to ensure that at least it has a sleeping move and good defense.