Sure, Donphan is bulky. But that begs the question, "Why not just use Hippowdon?" Hippowdon is far bulkier than Donphan (especially in terms of special bulk), has Whirlwind to prevent itself from being major setup bait, and, most importantly, reliable recovery. This allows it to function as a far better wall than Donphan ever could. Yes, Donphan has Rapid Spin, but it is bad on offensive teams because it has very little offensive presence, and it is mediocre on defensive teams because it has no recovery and is straight-up outclassed as a wall by Hippo. Offensive teams would much, much rather use Excadrill or Starmie if they needed to remove hazards for obvious reasons, whereas defensive teams have Defog Skarmory and Mandibuzz to remove hazards without wasting a slot on an otherwise bad Pokemon in Donphan. Donphan is outclassed in any role it can perform on both offensive and defensive teams.
And to the guy who mentioned using Gunk Shot, Thunder Fang, or Bounce on Donphan: No. Just no.
Because donphan is a bulky utility mon. He's a hazard clearer as well as a spinner who can get the spin off more than excadrill.
Yes, excadrill has mold breaker eq which can wreck gengar.... As can donphan's knock off, while also being able to take a focus blast.
Why do you bother mentioning rotom at all? Donphan's job isn't to deal damage, but set up hazards, clear them, and tank certain Pokemon. Donphan does an excellent job of taking out deadly Pokemon that underestimate it:
4 Atk Donphan Rock Slide vs. 88 HP / 0 Def Talonflame: 340-400 (106.5 - 125.3%) -- guaranteed OHKO
As for dragonite...
4 Atk Donphan Rock Slide vs. 4 HP / 0 Def Multiscale Dragonite: 67-79 (20.6 - 24.3%) -- guaranteed 5HKO
Then
4 Atk Donphan Ice Shard vs. 4 HP / 0 Def Dragonite: 144-172 (44.4 - 53%) -- 26.2% chance to 2HKO
Meanwhile...
+1 252+ Atk Dragonite Dragon Claw vs. 252 HP / 252+ Def Donphan: 141-166 (36.7 - 43.2%) -- 98.2% chance to 3HKO after Leftovers recovery
And we all know dragonite rarely runs adamant.
Oh, about that quad weakness you mentioned earlier (you used lando-t who donphan has no business staying in on because if a lando t is sent in on donphan its to put up rocks which donphan can reliably do while tanking any attack lando sends its way)
Here's garchomp
4 Atk Donphan Ice Shard vs. 4 HP / 0 Def Garchomp: 144-172 (40.2 - 48%) -- 5.1% chance to 2HKO after Stealth Rock
Meanwhile...
252 Atk Garchomp Dragon Claw vs. 252 HP / 252+ Def Donphan: 84-99 (21.8 - 25.7%) -- possible 5HKO after Leftovers recovery
Double the damage out put after a SD and you got a possible KO but no luck there because ice shard will wreck.
My point is you scorn donphan because it doesn't have the offensive presence of excadrill nor the bulk or utility to rival hippowdon, which, physically it does.
Excadrill is an offensive speedy spinner, compare it to starmie, not donphan.
As for hippowdon, your claims of it having better utility is laughable.
Donphan gets roar to match whirlwind.... As well as rocks, rapid spin, sandstorm, sunny day, endeavor, knock off, AND priority and sturdy as a safety cushion.
C'mon. This hatred toward donphan is because he isn't flashy, isn't new, and doesn't command the scene but works tirelessly to do the mundane work that needs to be done, a true tank tread.