I finally got the perfect OHKO with Miraidon that I was imagining. To save animation time, I opted to use Life Orb over Throat Spray and still used the Charge + Metal Sound + Attack Cheer setup, which may take a roll to kill even with the NPC damage.
252+ SpA Life Orb Hadron Engine Miraidon Atk Cheer charged Electro Drift (133.3251953125 BP) vs. -2 0 HP / 0 SpD Tera Water Samurott-Hisui in Electric Terrain: 9431-11098 (83.9 - 98.7% of 35x hp boss) -- guaranteed 2HKO
Step 0: Rig for a mon that can set paralysis (Dudunsparce/Umbreon preferred) in slot 2/3, because slot 1 will spend its T1 using Defense Cheer. Paralysis is necessary to stop Bulldoze from happening, which cannot miss and takes up time to display each speed drop animation. Here I got Haxorus in slot 2, but Haxorus prefers to Scary Face early anyway, so it won't trigger Bulldoze by attacking before paralysis goes up. Dudunsparce and Umbreon will prefer to Glare/Thunder Wave when no status is present, which is more reliable than Bellibolt's Discharge that will immediately trigger Bulldoze.
Step 1: Use Charge. In this attempt I even got a Ceaseless Edge T1 miss (10%), which also saves time not displaying the spikes animation and text. I also got the 25% paralysis to block Bulldoze from Umbreon's Thunder Wave (90% accurate).
Step 2: Use Metal Sound (85% accurate). Samurott loses its turn to another 10% miss, with the alternative of 25% paralysis leading to an overall 32.5% chance of Samurott losing a turn here. I think a miss is better time-wise because paralysis still plays a small animation.
Step 3: Attack cheer. Samurott loses its turn to paralysis here. I think an attack cheer is faster than using Calm Mind here because it doesn't have to mention boosting SpD, and it resets the menu for the next turn.
Step 4: Electro Drift for the near-OHKO. You can mash A at this point, since after a cheer your cursor is placed on Battle and moveslot 1.
Overall this is probably the fastest win you can get outside of relying on a critical instead of the attack cheer. I would say an intimidator is preferred so you can actually take more than 1 Ceaseless Edge, but dodging Bulldoze was the main goal and you have a good chance of dodging the remaining attacks after paralysis. If you invest in Defense instead of HP, then you can also take 1 more hit naturally after the defense cheer.
How close was this raid? I timed the shield's 87% activation time from the first possible input (Battle screen appearing, after ability text and Samurott's Swords Dance) while idling and came to about 1 minute and 2 seconds, which estimates the whole raid to last about 8 minutes long. The length of my clips from that point total to 30 + 17 + making the final input at about 6 seconds in for 53 seconds, so it was still close even with never getting hit and I probably couldn't have taken another turn of setup, but 9 seconds was probably enough spare time for a Ceaseless Edge to hit and set spikes. As for chance of success, disregarding the initial prep to get a winning team, the chance of a Ceaseless Edge miss + Umbreon's Thunder Wave + Bulldoze paralysis + Metal Sound landing + 2 missed turns comes down to about 0.2% or 1/500 odds for this particular attempt.