Donphan
It's rating is 9
However how much do we know about that?
As attacker and defender.
Answers
He is great on defense because he only has a single weakness, not a double weakness like Rhydon, Gyarados, and Dragonite. Everything has a weakness, but it is those with the double weaknesses that fall quick. He is like Vaporeon in the respect that he has good stats and only a single weakness, which makes him much bulkier than Rhydon. In addition to that, counter is a good defensive move, doing over 4 DDPS. Both play rough and heavy slam are 2 bar moves, which are idea on defense, and PR, in particular, comes on very fast. Tackle is more comparable to bite on defense...so not good at all.
He can also excel on offense. Counter is probably the most popular offensive move, because of Snorlax and Blissey, and he has access to it. Everyone talks about Usaring, but not Donphan...His good attack stat make EQ a powerful attack. Obviously his biggest flaw is no STAB quick move, but tackle is still a solid move in that it is very quick, .5 cooldown, and has an EPS of 10, which builds energy pretty quickly.
He is solid all the way around, his cp just keeps him out of many gyms.
It's decent. Good stats, with mediocre moves.
While counter is good on offense in the current meta due to being SE vs. the top defenders, it lacks STAB and therefore is not optimal.
On defense, counter also suffers from lack of STAB. 12 power without STAB is subpar, though better than for example WG from Vape. It also hits NVE into Venusaur and Exeggutor, two very viable attackers into Donphan.
Play Rough also lacks STAB, but is a very powerful move regardless. It hits quick and hard on defense, dealing neutral damage to most attackers (the most notable exception is Venusaur, who resists it).
My personal experience is that Donphan is serviceable on both offense and defense, but is an unlikely pick for a trainer with a large roster due to being overshadowed by other pokemon.
What makes him attractive to me is that he is a viable but at the same time uncommon defender.
While Ursaring is good, he's not optimal either. I do have both an Ursaring and a Donphan, and I believe they're about equally good at attacking.
Ursaring has been a bit over hyped in threads here lately. If people actually tried him out, they would see that he's overshadowed by Machamp, Exeggutor, Dragonite, Tyranitar, Heracross, Flareon ++. That can also be seen here: https://pokemongo.gamepress.gg/best-ways-beat-down-blissey and here: https://pokemongo.gamepress.gg/besting-big-7-defenders.
So no, neither Ursaring nor Donphan are optimal. They are, however, pretty good.