Moves
Beyond the obligatory Rapid Spin, Earthquake gives Donphan the power to threaten Tyranitar and Steel-types such as Metagross, Jirachi, and Lucario, as it generally at least 2HKOes foes weak to it. Donphan’s physical bulk and the threat of Rapid Spin affords it the turn it needs to set up Stealth Rock.
As Donphan only needs Earthquake and Rapid Spin, it has a wide variety of available options, especially if another Pokemon can set up Stealth Rock. Odor Sleuth is excellent for more defensive approaches, as it guarantees Donphan will be able to use Rapid Spin, even against Ghost-types, especially when paired with Rest to heal off burns and keep Donphan alive against residual damage. Ice Shard is effective on more offensive slants, as despite the fact it’s weak, it gives almost perfect coverage and helps to revenge kill foes 4x weak to it like Dragonite, Flygon, and Gliscor.
Knock Off is also very effective at removing items from Ghost-types and other Ground-immune Pokemon. It also helps break opposing Donphan. With Stealth Rock up, Assurance is an excellent option to hit Ghost-types on the switch, as it OHKOes Gengar and offensive Rotom-A. Unfortunately it doesn’t do enough damage to them if Donphan doesn’t predict the switch-in due to the power loss. Head Smash is another option, as hits Gengar and Gyarados very hard, but the accuracy and recoil are painful and it doesn’t have much utility against defensive Pokemon.
Set Details
As Donphan only needs 252 HP EVs to do its job, it has a wide variety of available EV spreads. That said, maximum Defense EVs and an Impish nature is very helpful to help it against Tyranitar, physical Dragonite, Metagross, and Jirachi, as the increased bulk allows Donphan to withstand multiple attacks against Dragon Dance and other physical sweepers and either retaliate or Rapid Spin away Stealth Rock.
Donphan can also fully invest in its Special Defense with a Careful nature to better survive attacks from Gengar, Rotom-A, and Heatran, but the loss in physical bulk is noticeable. Donphan can also use an Adamant nature and heavy Defense investment, especially with Assurance or Head Smash, as the nature guarantees an OHKO on Gengar while KOing Rotom-A on the next switch in of Stealth Rock.
Usage Tips
How Donphan should be played generally depends on if it has Stealth Rock. Stealth Rock Donphan typically hits the field fairly early to set up Stealth Rock on Pokemon that don't threaten it very much such as Tyranitar. However, without Stealth Rock or if Stealth Rock is already up, Donphan typically is played more cautiously, as it has lopsided defensive stats and despises status and residual damage. Donphan's teammates typically don't 100% need Stealth Rock off at all times; KOing or otherwise heavily weakening the opposing entry hazard user and then sending in Donphan to spin away the entry hazards can make Donphan's job way easier. However, if Donphan is needed defensively, do not hesitate to send it in, as a full health physically Donphan will stop most physical sweepers besides Gyarados. Predicting Ghost-types switching in can be very helpful in weakening them, regardless if Donphan has Assurance or not. If Toxic Spikes are up and Donphan doesn't have Rest, be very careful about when you decide to send it in, as you can only remove them once before Donphan is permanently incapacitated.
For more defensive teams with two Rapid Spin users, Donphan should often be the second one sent in, as both Forretress and Starmie better handle Ghost-types. Before Donphan's two additional moves are revealed, they can potentially catch the opponent offguard, so don't hesitate to take advantage of this.
Team Options
Donphan is highly effective on more balanced teams to support offensive threats such as Choice Band Tyranitar, Choice Specs Heatran, and Choice Specs Empoleon alongside a strong defensive core. It also is very effective supporting Pokemon like Machamp and Gyarados alongside paralysis support, and with another spinner such as Starmie or Forretress to support Pokemon debilitated by entry hazards such as Zapdos, Abomasnow, and Togekiss.
Donphan is fantastic alongside physically defensive Zapdos, as it can Rapid Spin for it, Donphan helps against Dragon Dance Tyranitar, and Zapdos covers many Water- and Grass-types Donphan loathes to take on. Jirachi is also an excellent partner, as Donphan removes Spikes and Jirachi is bulky enough to deal with many special attackers such as Latias and can provide Wish support for Donphan. This partnership is fantastic in supporting strong Choiced wall breakers, as Zapdos, Donphan, and Jirachi cover much of the metagame between them. Choice Band Tyranitar and Choice Specs Heatran are fantastic against Rotom-A, as Tyranitar traps it and Heatran gets a Flash Fire boost from Will-O-Wisp. Bulkier Water-types such as Milotic and Slowbro are also excellent partners to give a sturdy Water- and Fire- resistance as well as spread paralysis.
For more offensive partners, Gyarados and Machamp are excellent options. Removing entry hazards are paramount for these Pokemon, especially Stealth Rock for Gyarados and (Toxic) Spikes for Machamp. In return, they provide offensive pressure and potentially KO entry hazards users so Donphan doesn’t have to Rapid Spin them away again. Donphan also supports Choice Scarf Latias well due to handling Dragon Dance Tyranitar. Another way to help Donphan clear Stealth Rock is to either use a Trick + Choice Scarf lead such as Uxie, Metagross, Azelf, or Latias, or use Magnezone or Magneton to trap them. Locking often slower Stealth Rock users into a move or trapping Steel-types helps Donphan a lot in removing entry hazards.
For more defensive teams, Donphan can support teammates heavily hampered by entry hazards. More defensive partners such as Clefable and Blissey are excellent partners, as they can potentially use Heal Bell for Rest Donphan. Other Rapid Spin partners such as Tentacruel can work, as can Pokemon that don’t enjoy Spikes and let them up easily such as Swords Dance Breloom and Calm Mind + Rest Suicune. Donphan can potentially support very uncommon Pokemon such as Moltres, Registeel, and Yanmega deal with entry hazards.