So Beautimoth is completely under my radar, because it can't tank and is slow
Beautimoth stats:
80 hp, 120 atk, 70 def, 70 agi total: 340
A better stat spread is Soliche who is both fast and strong with a great Personaility skill.
Soliche stats:
70 hp, 140 atk, 80 def, 110 agi total: 400
For Dark mons non DLC2, Kurotorofu/Shadoom is easily the best, it has a great personality skill and tank stats with a very optimized moveset to tank with.
Kurotorofu/Shadoom stats:
70 hp, 90 atk, 130 def, 70 agi total: 360
And for water, Snaildome has minmaxed defense stats allowing it to be a soft body tank to absorb DoT status attacks often used by Dark mons and heal it off.
Snaildome stats:
80 hp, 60 atk, 130 def, 30 agi total: 300