From Halopedia, the Halo wiki
Halo 5: Guardians
Goblins are typically bosses in Warzone and Warzone Firefight. Extremely durable and capable of outputting mass amounts of damage while keeping mobile it regularly takes multiple well armed players to take down a single Goblin. By far the most effective way to combat any Goblin is to use a Phaeton Helios. D'nomlhe-pattern Banshees can also perform well, but often have to make multiple runs against the Goblin. M820 Scorpions and Kemu-pattern Wraiths are decent options, sometimes even being capable of destroying the Goblin's shield, although they are vulnerable due to their slow speed. Using cover and "shoot and scoot" tactics are advised. While certain weapons like the Talon of the Lost, Twin Jewels of Maethrillian, and Type-50 Delta are effective against the Goblin or at least good at piercing its shield, players will have to use most if not all of the gun's ammo.
Halo Wars 2
Goblins are exclusive to Yapyap and can be made at War Councils. Unlike other hero units each player can use up to three Goblins at once, similar to how Spartan-II worked in Halo Wars. Unupgraded Goblins do well against vehicles, but only okay against infantry, aircraft, and structures. Once upgraded with Ultra Hustle Goblins will perform well against infantry. In Blitz a Goblin costs 180 energy.