Torterra works wonders in this raid. I challenged twice (Scarlet and Violet) and caught it both times.
Torterra @ Shell Bell (Tera Type: Dark)
Impish Nature | Shell Armor
252 Atk, 252 Def, 6 HP
- Crunch
- Iron Defense
- Swords Dance
- Synthesis
It is important that one of the computer partners is a Pokémon that has intimidate as an ability (First time I got lucky with Tauros and Staraptor both times). Start boosting defense with Iron Defense until the stat wipe, healing when necessary. After that, Iron Defense three times followed by three Swords Dance, three Crunch, then Tera-Crunch until you win.
Two Intimidators makes it even easier. My second time I had two with intimidate and Toxapex throwing Chilling Water.
Torterra has shell armor which prevents those crits making those attack drops actually matter. Tyranitar is annoying but suffers from having an exploitable weakness.