In terms of weapons, the Water element is the way to go. There are a few options across all the weapons here, though Balahara and Uth Duna are the most widely available ones to aim for.

Its whole body is weak to Water, Ice ... the Bone Armor set and its 15 points of elemental resistance against Thunder-type damage will suffice. The Guardian Fulgur Anjanath is a massive monster ...

However, you can use the crystals to your advantage if you've got any elemental ammunition in your Slinger. Image credit: Eurogamer/Capcom There will also be times that Guardian Ebony Odogaron ...