At first glance, Throh seems to be outclassed by other Fighting-types, with no hope of showing up amongst powerful Pokemon such as Conkeldurr. This is only partially the truth. While it is true that Throh is less popular and can do fewer things more effectively than other Fighting-types, he does have a couple of tricks up his sleeve. Throh is the bulkiest Fighting-type that exists in the game, with base 120 HP and 85 defenses, meaning he can tank hits more effectively than similar Fighting-types. Throh also has a great phazing move in Circle Throw, which does modest damage while forcing the opponent out. This means Throh can phaze even when under the effects of Taunt, and being the bulkiest Fighting-type to do so gives Throh a useful niche in the OU metagame.
Throh fulfills his niche by using a combination of Bulk Up and Circle Throw, allowing him to beat other Bulk Up users such as Scrafty and Conkeldurr. Bulk Up is the main move of this set, making Throh extremely hard to take out after just one boost. The main choice for a STAB move is Circle Throw, which allows Throh to force out other Pokemon that try to force him out themselves. Storm Throw is a useful alternative, as it always gets a critical hit. That means it always breaks through the defense boosts of other Bulk Up users.
The other two slots have three options to consider. Payback is the best choice for a coverage move, allowing Throh to hit Gengar and Jellicent, which are immune to Circle Throw. Rest is the favorable fourth move on this set, since Throh needs a way to heal off damage and can actually survive the sleep turns in many situations. Stone Edge is the alternate choice in either slot, as it does hit Flying-types such as Gyarados and Salamence super effectively. The other two moves have more utility, however, meaning Stone Edge is less attractive of an option.Team Options & Additional Comments >>>
Throh's niche is the only reason why he should be used, meaning he has very few other viable options. The only real choice to consider is Toxic, letting Throh cripple other Pokemon himself. However, pairing Throh with a Toxic Spikes user is far more effective in order to save a moveslot.
Checks and Counters
Skarmory is the best counter to Throh, as it can take boosted Fighting-type moves and use Whirlwind before Throh uses Circle Throw. Swampert and Suicune, although relatively uncommon, do a similar job with Roar. In addition, any Pokemon with a super effective STAB move can give Throh problems. Dragonite and Tornadus need to avoid Stone Edge, but Hurricane deals massive damage to Throh. Reuniclus is slower than Throh, meaning it avoids taking double damage from Payback, and Psychic deals major damage. Togekiss and Yanmega also worry about Stone Edge, but can carry a powerful, super effective Air Slash. Lastly, Trick users cripple Throh since he needs to be able to switch moves to be useful. A Throh locked into the wrong move can be easily used as setup bait by the appropriate Pokemon.
Throh gets Mold Breaker from the Dream World, which is an interesting ability choice. It would allow Throh to hit Gengar, Bronzong, and Rotom-A with Earthquake, which is extremely helpful. It is usually superior to Guts on any Throh using Rest, as those don't fear status at all. In the case that Throh chooses not to carry Rest, Guts is the superior choice to take advantage of any status he takes.