Crawdaunt is an amazing offensive mon overshadowed by greninja, but still has a role it helps with some match-ups some notable ones being steel/ground/flying, and crawdaunt's adaptability aids its overall offensive presence, aqua jet is a solid priority stab. Also, jolly to out speed Rotom-W. Dragon Dance is an option but you really shouldn't run it over sd.
Mandibuzz is a staple on balance dark and offers great defensive presence, is basically the types only defogger, helps in the fighting match-up, 16 speed is for azumarril and scizor, standard mixed defensive spread and taunt>knock off to stop slower mons from getting hazards/recovering/defog/setup.
Tyranitar is the teams dedicated stealth rocker, with fire blast + rockslide for standard coverage, thunder wave speaks for itself to be quite honest, and chople is for allowing ttar to live fighting moves notably chary's focus blast , scarf keldeos ecret sword (Secret Sword does 74 with an absolute max roll), even giving it a chance (which is in your favor) to live terrakions close combat, and then max spdef speaks for itself + sand.
Muk has become a staple on most balance dark teams this gen and for good reason as it serves as a hard check to magearna, it also has the ability to 1v1 tapu koko/tapu bulu/clefable/gardevoir mega. With fire blast muk is 3hkoing offensive variants of magearna and doing 20% to av magearna however both variants have no way of killing muk aside from a +1 twinkle tackle from offensive but that can be played around the still be 1v1ed with muk. With pursuit, knockoff, poison jab muk has solid stab moves to compliment it, you could also run stone edge/shadow sneak but i feel both of these are worse options.
Originally i had houndoom and had no intent on changing it at first however after looking over my team, and noticing how much i had to beat steel i realized i could run sableye which is doing more for me in the long run. I'm running the standard knock off + foul play set with standard mixed evs. Sableye is a great defensive backbone which helps in the team in most match ups most notably being breaking normal with crawdaunt or alone if played well.
A solid staple on dark, greninja brings amazing coverage speed and special attack. On this set i'm running pretty standard coverage and the set basically speaks for itself, but HpFire > HpElectric for the steel match-up which i felt i could use some help in after changing houndoom and extrasensory for toxapex/venusaur/fighting types. As the team lacks a scarfer you can replace the life orb with a scarf for great speed control