Ferrothorn is an excellent defensive Steel-type and entry hazard setter, since its Grass typing lends it resistances to Water and Electric as well as a neutrality to Ground, allowing it to more comfortably handle Pokemon like Ogerpon-W, Mega Swampert, Tapu Koko, and Raging Bolt, which other Steel-types like Mega Scizor and Gholdengo have more trouble against; being a Steel-type also naturally improves its matchup against Melmetal, Tapu Lele, and Rillaboom. Iron Barbs lets Ferrothorn pressure foes like Urshifu-R, Mega Lopunny, Melmetal lacking Protective Pads, and U-turn users like Landorus-T, forcing them to play more carefully lest they rack up chip damage very quickly with contact moves. Leech Seed is Ferrothorn's most reliable recovery, allowing it to pressure other passive Pokemon like Toxapex and Gliscor into wasting their healing moves, deal valuable chip damage to switch-ins that have no means of healing such as Cinderace and Heatran, and gradually recover HP with each use. Knock Off allows Ferrothorn to punish Heavy-Duty Boots users like Zapdos, Toxapex, and Tornadus-T as well as Leftovers users like Landorus-T, which is extremely valuable in forcing progress by making foes more susceptible to hazards or removing their recovery. Body Press allows Ferrothorn to surprise Kingambit and Kyurem, dealing massive damage to both and avoiding getting PP stalled by Kyurem; it also lets Ferrothorn hit Heatran on the switch and damage opposing Ferrothorn instead of idling. Gyro Ball snags Fairy-types like Tapu Lele and Iron Valiant on the switch and is better neutral coverage against foes like Dragonite, although it should be run with a Relaxed nature and 0 Speed IVs. Thunder Wave is niche, providing great value against offense teams, but since it is easily blocked by Gholdengo, it is often undesirable. Spikes is used over Stealth Rock when another setter is present on the team. The Special Defense EVs allow Ferrothorn to survive Choice Specs Tapu Lele's Focus Blast from full HP. Leftovers is nigh mandatory, providing much more consistent healing than Leech Seed and taking advantage of Ferrothorn's ability to sit on the field for many turns at a time. Rocky Helmet is a viable alternative, punishing U-turn users like Landorus-T and Urshifu-R as well as Rapid Spin from Great Tusk much harder; overall, it rewards risky play compared to Leftovers’s relative safety and should therefore allow Ferrothorn to be used more aggressively.

Most wallbreakers pair well with Ferrothorn, taking advantage of the entry hazards it sets to break through defensive targets, but those that switch in on Ferrothorn's counters such as Gholdengo, Zamazenta, and Mega Charizard Y are particularly good; these wallbreakers include Kingambit, Mega Charizard Y, Tapu Lele, and Mega Tyranitar; Kingambit and Mega Tyranitar can also Pursuit trap Gholdengo. Gholdengo itself is also a good teammate, as it can deny Defog and switch in more easily against Pokemon like Tapu Lele and Iron Valiant. Ferrothorn's defensive utility is also appreciated by teammates like Toxapex and Landorus-T, which struggle with Electric-types like Tapu Koko and Water- and Ice-types like Hisuian Samurott and Kyurem, all of which Ferrothorn helps check. However, Ferrothorn does have a host of issues that require some support to cover. Ferrothorn's glaring Fire weakness is not even its biggest problem, given that having teammates like Toxapex, Heatran, and Alomomola around can easily blank Fire-type moves from the likes of Mega Charizard Y and opposing Heatran. Its main problem stems from its lack of instant recovery, making it more inclined to offensively oriented teams. Having Leftovers removed by Knock Off from foes like Kingambit, Mega Tyranitar, and opposing Ferrothorn or getting burned by Scald from foes like Toxapex renders it unable to heal without Leech Seed, and Leech Seed fails against Gholdengo and common Grass-types like Ogerpon-W and opposing Ferrothorn. Therefore, Ferrothorn is best played more offensively, using its unique defensive utility, Leech Seed, and Iron Barbs to force switches and hazard chip damage, granting immediate momentum when played aggressively while also not punishing the user for playing more carefully. Teammates that can absorb Knock Off, like Mega Tyranitar, and those that can absorb Will-O-Wisp, like Heatran and Clefable, are incredibly valuable teammates. Finally, Pokemon that can cover Ferrothorn's Fighting weakness are good defensively, including the aforementioned Gholdengo as well as Zapdos, Landorus-T, and Toxapex.