The first thing you should know is that there's no such thing as a "practically unstoppable" strategy in competitive Pokemon. Even though Pokemon isn't the most balanced video game out there, the Pokemon Company still organizes multiple tournaments with hundreds of participants each year. If a "practically unstoppable" strategy exists, would you really expect none of those tournament players to know about it?
The second thing you should know is that this wouldn't work in gen 9 because Shedinja isn't obtainable in gen 9.
So let's say you still want to attempt this in gen 8, even though you know it'll eventually fail. Skill swap doesn't work on wonder guard, so you would need either entrainment or gastro acid. No Pokemon learns both gastro acid and entrainment in gen 8, and the only Pokemon that learns gastro acid and skill swap is Mew, which is banned in VGC22.
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You would need to switch after using gastro acid. This effectively gives the opponent 2 opportunities to attack an ability-less Shedinja (1 opportunity with protect, but that costs an entire move slot on Shedinja). So a gastro acid strategy can be stopped by any Pokemon with a non-normal attack.
Entrainment isn't that much better. The only Pokemon that learns entrainment and skill swap is Audino, and the only Pokemon that learn entrainment and role play are Lilligant and Audino. Lilligant's speed won't matter here because it's still slower than almost all the offensive Pokemon in VGC22, so let's use Audino. Audino will need to survive 2 turns in order to transfer sturdy onto Shedinja. This is what happens if Audino attempts to survive 2 turns against the most common offensive threats in VGC22 (ignoring Dynamax).
252 SpA Solar Power Charizard Blast Burn vs. 252 HP / 128+ SpD Audino in Sun: 229-270 (109 - 128.5%) -- guaranteed OHKO
156+ SpA Kyogre Water Spout (150 BP) vs. 252 HP / 128+ SpD Audino in Rain: 198-234 (94.2 - 111.4%) -- 68.8% chance to OHKO
132+ Atk Groudon Precipice Blades vs. 252 HP / 128 Def Audino: 114-135 (54.2 - 64.2%) -- guaranteed 2HKO
+1 196+ Atk Zacian-Crowned Sacred Sword vs. 252 HP / 128 Def Audino: 196-232 (93.3 - 110.4%) -- 62.5% chance to OHKO
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In short, no
