Diggersby will run with a lot of sets and combinations. He can use Assault Vest, Life Orb, Choice Band, Scarf, etc.
Well let's see:
Notable New Moves:
Knock Off, Focus Punch, Foul Play, Superpower, Iron Tail, Thunder Punch, Fire Punch, Ice Punch, Iron Head, Low Kick, Gunk Shot
How can it work in metagame?
252+ Atk Huge Power Diggersby Knock Off (97.5 BP) vs. 28 HP / 0 Def Gengar: 414-488 (154.4 - 182%) -- guaranteed OHKO
252+ Atk Huge Power Diggersby Knock Off (97.5 BP) vs. 248 HP / 252+ Def Gothitelle: 204-242 (59.4 - 70.5%) -- guaranteed 2HKO
252+ Atk Huge Power Diggersby Knock Off (97.5 BP) vs. 4 HP / 0 Def Latios: 328-388 (108.6 - 128.4%) -- guaranteed OHKO
252+ Atk Huge Power Diggersby Knock Off (97.5 BP) vs. 0 HP / 0 Def Latias: 300-354 (99.6 - 117.6%) -- 93.8% chance to OHKO
252+ Atk Huge Power Diggersby Knock Off (97.5 BP) vs. 252 HP / 0 Def Mew: 274-324 (67.8 - 80.1%) -- guaranteed 2HKO after Leftovers recovery
252+ Atk Huge Power Diggersby Superpower vs. 252 HP / 88+ Def Ferrothorn: 226-268 (64.2 - 76.1%) -- guaranteed 2HKO after Leftovers recovery
252+ Atk Huge Power Diggersby Superpower vs. 252 HP / 252+ Def Eviolite Chansey: 448-528 (63.6 - 75%) -- guaranteed 2HKO (consider Knock Off now)
252+ Atk Huge Power Diggersby Superpower vs. 0 HP / 4 Def Mega Gyarados: 314-370 (94.8 - 111.7%) -- 68.8% chance to OHKO
-1 252+ Atk Huge Power Diggersby Ice Punch vs. 0 HP / 0 Def Landorus-T: 308-364 (96.5 - 114.1%) -- 81.3% chance to OHKO
252+ Atk Huge Power Diggersby Ice Punch vs. 0 HP / 0 Def Garchomp: 444-524 (124.3 - 146.7%) -- guaranteed OHKO
252+ Atk Huge Power Diggersby Ice Punch vs. 252 HP / 252+ Def Gliscor: 264-312 (74.5 - 88.1%) -- guaranteed 2HKO after Poison Heal
252 Atk Huge Power Diggersby Iron Head vs. 0 HP / 24 Def Mega Gardevoir: 282-332 (101.8 - 119.8%) -- guaranteed OHKO
252 Atk Huge Power Diggersby Iron Head vs. 252 HP / 4 Def Sylveon: 290-342 (73.6 - 86.8%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Huge Power Diggersby Iron Tail vs. 252 HP / 4 Def Sylveon: 362-428 (91.8 - 108.6%) -- 50% chance to OHKO
252 Atk Huge Power Diggersby Gunk Shot vs. 92 HP / 0 Def Azumarill: 372-438 (102.1 - 120.3%) -- guaranteed OHKO
Nothing will enter really safe in Diggersby. Maybe Skarmory. A bulky set can resist to Charizard Y, Mach Punch Breloom, Manectric HP Ice, etc.