Mandibuzz and Honchkrow work completely differently, if you want to tank use Mandibuzz, if you want to be a frail attacker use Honchkrow.
Alolan Dugtrio is bad, consider replacing it for another ground or steel type, whichever you want. Garchomp, Mamoswine, Krookodile for ground types and Celesteela, Kartana, Aegislash, Magnezone, Scizor for steel type and Mega Metagross and Mega Lucario are also cool options for the mega slot.
Don't be shy to use the Tapu's either. Your opponent is almost definitely gonna use at least one of them and all of them are great.
If you are looking for a ghost type that can take hits then Alolan Marowak is the best, sporting 3 immunities with the lightning rod ability and can hit hard as well when it's holding thick club. Mimikyu is usable but can be harder to use well since it's ability only works once, Gengar is also a option but it is a glass cannon.
Oranguru is kinda meh, it's gimmick doesn't work in singles format so consider replacing it with a different mon if you are playing singles.
Hariyama is pretty solid.
Kommo-o is pretty meh honestly, everything it can do something else can do better. But the best set is probably dragon dance set dragon claw/outrage, sky uppercut and poison jab as attacks. It can also be a special attacker with clanging scales, focus blast, flamethrower and flash cannon. Autotomize can also be used when you want it go be faster (and lighter).
Also, be careful relying on immunities to get a defensive synergy. Most pokemon in the competitive scene have dual typings and use more than one move of a type so they will usually have something for your ghost/ground/steel/fairy type and some of them just have great offensive typings so you can't rely on immunities to beat the likes of Mamoswine and Garchomp.