After defeating the Elite Four and finishing the main storyline, you will be able to start battling and catching the Ultra Beasts through the Looker Storyline. The fifth and final Ultra Beast you are set to capture is Guzzlord. Like all Ultra Beasts, Guzzlord has some pretty incredible Stats. It's more of a Physical Tank Pokemon, with extremely good stats in both its HP and Attack. Literally, Guzzlord is like a Chansey or Blissey, but one that can actually attack. Luckily it's only a Dark/Dragon Type, allowing it to be paralyzed.
Here Are Some Tips For Catching Guzzlord:
Unlike many of the other Ultra Beasts, you are only set to catch one Guzzlord. It can be found randomly in the basement of Resolution Cave. Since it's at Level 70, a player can easily put a Level 60 Pokemon at the lead of their party and use a Repel to quickly find Guzzlord in this area. A player will know they are near this Ultra Beast by a change in the music and a not-so-far off cry from it.
Right as the Battle begins, Guzzlord's already amazing Attack will increase by two stages, making it a serious threat. The first thing you can do to limit it is by paralyzing it on the first turn in battle, making it easier to capture later in the battle. Steel Type Pokemon actually fair well against Guzzlord, since it mainly uses Steel and Normal Type Attacks of its own. From there, try to lower Guzzlord's HP as low as you possibly can. Moves like False Swipe and Hold Back work great when it has low HP, ensuring to leave at least one HP. The lower it's HP is, the better chance you have at catching it. But don't get Guzzlord's HP too low, because it loves to use Thrash and could make itself faint from its recoil damage of confusion.
But make sure to keep track of the more Pokemon Guzzlord knocks out on your team, as its Highest Stat will increase every Time it does so because of its Beast Boost Ability. Because of this, like all the other Ultra Beasts, it's best to try to capture it as quickly as possible with the Beast Ball, since it has a x5 Catch Rate with Ultra Beasts. There is no need to use any other type of Poke Ball, since this is the last Ultra Beast needing captured.
And don't forget to ALWAYS save before trying to find Guzzlord. It's a safety precaution, one that has worked since the first generation of Pokemon.