Gholdengo

Gholdengo has the huge honor of being Pokemon #1,000, one of the greatest milestones in the entire series. However, that distinction doesn't exactly make it good. Ghost is its only viable attacking type, and it's pretty outclassed on that front. And even if it had a Steel Type moveset, that's another type that has huge competition. It seems that Gholdengo just has no real utility at the moment.

Best PvE Offensive Moveset

• Hex and Shadow Ball is a great Ghost Type moveset, and Gholdengo's best offensive moveset.
• Astonish, Dazzling Gleam, Power Gem, and Focus Blast aren't great options.

Best PvE Defensive Moveset

• Hex is Gholdengo's best defensive Fast Move, easily out-pacing Astonish. 
• Dazzling Gleam isa great option on defense, as it comes out fairly early and has great coverage alongside Hex.
• Power Gem is a bit weaker, but it has wide coverage and comes out pretty quickly.
• Shadow Ball is objectively good, but it shares a type with Hex, meaning it can easily be walled by Dark or Normal Types
• Focus Blast has perfect coverage with Hex, resisted only by Hisuian Zorua/Zoroark. But its high cost makes it pretty unreliable on defense.

Astonish and Hex are about equally good. Astonish has higher damage, but Hex's improved energy generation helps with reaching Gholdengo's moderately expensive Charged Attacks

Shadow Ball is Gholdengo's bread and butter STAB attack, having solid DPE. Power Gem is typically the preferred secondary attack, as it is Gholdengo's cheapest attack and provides coverage against Fire-type enemies. Focus Blast is extremely expensive, but it has great DPE and offers nigh unresisted damage when combined with Shadow Ball. Dazzling Gleam's coverage also pairs well with Shadow Ball, but it has less DPE and doesn't have as wide of a coverage as Focus Blast does.