Check

Samurott-Hisui @ Heavy-Duty Boots
Ability: Sharpness
Tera Type: Fire
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Ceaseless Edge
- Razor Shell
- Knock Off
- Encore / Aqua Jet
Samurott can take any one hit and OHKO in return, since Iron Moth is weak to water with or without tera. If you bring Aqua Jet, you can set up a layer of spikes and still win.
132 SpA Iron Moth Sludge Wave vs. 0 HP / 4 SpD Samurott-Hisui: 213-252 (66.3 - 78.5%) -- guaranteed 2HKO
252 Atk Sharpness Samurott-Hisui Razor Shell vs. 0 HP / 124 Def Iron Moth: 408-480 (135.5 - 159.4%) -- guaranteed OHKO
252 Atk Sharpness Samurott-Hisui Ceaseless Edge vs. 0 HP / 124 Def Iron Moth: 177-208 (58.8 - 69.1%) -- guaranteed 2HKO
252 Atk Samurott-Hisui Aqua Jet vs. 0 HP / 124 Def Iron Moth: 146-174 (48.5 - 57.8%) -- 93.4% chance to 2HKO
Counter

Araquanid @ Focus Sash
Ability: Water Bubble
Tera Type: Ghost
EVs: 248 HP / 192 SpD / 68 Spe
Careful Nature
- Liquidation
- Leech Life
- Mirror Coat
- Sticky Web
Araquanid can take any two hits from Iron Moth and OHKO regardless of tera. If the first hit isn't Fiery Dance (or if Iron Moth doesn't get the boost from Fiery Dance), Araquanid can survive three hits, giving it a turn to set up Sticky Web.
132 SpA Iron Moth Fiery Dance vs. 248 HP / 192+ SpD Water Bubble Araquanid: 40-48 (11.7 - 14.1%) -- possible 8HKO
132 SpA Iron Moth Sludge Wave vs. 248 HP / 192+ SpD Araquanid: 93-111 (27.4 - 32.7%) -- guaranteed 4HKO
+1 132 SpA Iron Moth Sludge Wave vs. 248 HP / 192+ SpD Araquanid: 141-166 (41.5 - 48.9%) -- guaranteed 3HKO
0 Atk Water Bubble Araquanid Liquidation vs. 0 HP / 124 Def Iron Moth: 344-408 (114.2 - 135.5%) -- guaranteed OHKO

Samurott-Hisui @ Heavy-Duty Boots
Ability: Sharpness
Tera Type: Fire
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- Ceaseless Edge
- Razor Shell
- Knock Off
- Encore / Aqua Jet
Samurott can take any one hit and OHKO in return, since Iron Moth is weak to water with or without tera. If you bring Aqua Jet, you can set up a layer of spikes and still win.
132 SpA Iron Moth Sludge Wave vs. 0 HP / 4 SpD Samurott-Hisui: 213-252 (66.3 - 78.5%) -- guaranteed 2HKO
252 Atk Sharpness Samurott-Hisui Razor Shell vs. 0 HP / 124 Def Iron Moth: 408-480 (135.5 - 159.4%) -- guaranteed OHKO
252 Atk Sharpness Samurott-Hisui Ceaseless Edge vs. 0 HP / 124 Def Iron Moth: 177-208 (58.8 - 69.1%) -- guaranteed 2HKO
252 Atk Samurott-Hisui Aqua Jet vs. 0 HP / 124 Def Iron Moth: 146-174 (48.5 - 57.8%) -- 93.4% chance to 2HKO
Counter

Araquanid @ Focus Sash
Ability: Water Bubble
Tera Type: Ghost
EVs: 248 HP / 192 SpD / 68 Spe
Careful Nature
- Liquidation
- Leech Life
- Mirror Coat
- Sticky Web
Araquanid can take any two hits from Iron Moth and OHKO regardless of tera. If the first hit isn't Fiery Dance (or if Iron Moth doesn't get the boost from Fiery Dance), Araquanid can survive three hits, giving it a turn to set up Sticky Web.
132 SpA Iron Moth Fiery Dance vs. 248 HP / 192+ SpD Water Bubble Araquanid: 40-48 (11.7 - 14.1%) -- possible 8HKO
132 SpA Iron Moth Sludge Wave vs. 248 HP / 192+ SpD Araquanid: 93-111 (27.4 - 32.7%) -- guaranteed 4HKO
+1 132 SpA Iron Moth Sludge Wave vs. 248 HP / 192+ SpD Araquanid: 141-166 (41.5 - 48.9%) -- guaranteed 3HKO
0 Atk Water Bubble Araquanid Liquidation vs. 0 HP / 124 Def Iron Moth: 344-408 (114.2 - 135.5%) -- guaranteed OHKO