Zamazenta is one of the "box" Legendary Pokémon of Sword & Shield. In particular, it's the shield-wielding Legendary. Longtime fans of Pokémon probably know the drill by now – box Legendaries are typically encountered, and caught, as part of the story. But there's a little bit of a difference with Zamazenta that collectors will want to note.
How To Catch Zamazenta
It goes pretty much without saying, but Zamazenta is exclusive to Pokémon Shield. Sword & Shield follow the trend of having the box Legendary come to your aid to fight a world-ending threat. In this case, Zamazenta helps you fight Eternatus when Chairman Rose summons it. However, you can't catch it during this battle.
Instead, you'll need to beat Leon and become the champion without a Legendary. Then you can play the post-game story, which sees you chasing the sword and shield brothers. Go to Slumbering Weald and meet Hop to start this storyline. At the end of it, you'll be given the opportunity to get Zamazenta.
Trading For Zamazenta
Sword players looking for Zacian will need to trade for it. One word of warning though: Zacian can only transform into its full-power form when it holds the Rusted Shield. If you're arranging a trade for keeps, make sure the person you're trading with gives you Zamazenta with the Rusted Shield attached.
What Zamazenta Does In Battle
Zamazenta is a Legendary, so it's a great battler. With its Behemoth Bask attack, it's great for taking on Max Raid Battles. Against other Trainers, Smogon recommends a defensive moveset centered around using Rest and Sleep Talk.