From the hunts I’ve done, this guy seems a lot easier to handle in groups. His main strength is the ability to overwhelm a single hunter into moving into the defense, but many of his attacks are strictly forward facing; his sides have some resistance, but he has minimal ability to protect his back legs. While I can’t guarantee you won’t end up with good ol’ XxEliteMaster47xX using low defense and fire weapons to prove his Alpha Status, a sort of reverse crowd-controlling, in which you provide too many targets for him to really force one into panic, can help take Rajang down. Just watch out when he’s enraged for his super; when it starts, scatter asap, because it can be hard to tell who he’s targeting, and a group cart is bad news. His super is telegraphed by him curling up a bit and snarling, sort of flexing his arms inward, almost like his transition into the red arm enraged mode. You can also use Rajang targetting someone else to learn his moves with less panic, but for the love of a Fatalis, don’t run in the corner like a Kut-Ku with its head chopped off. Dipping away to drink a quick potion so you don’t cart is fine, but no one likes a spectator.