The thing is, with this damn deer, it is nearly impossible to one shot this thing. The best option has always been just to use the move that it hates the most, taunt. It's why even in ubers, this thing is so goddamn strong because it is the best slow down sign to Miraidon, yes fking Miraidon, the very same one that some ubers players are considering as problematic. The thing even decides to abuse Koraidon's own sun and use an instant charge solarbeam to delete this deer. Anyways, in ou, there are several ways to one shot the damn deer. However, many of them need slight chip damage, weather conditions, or non ideal usage of tera. Here's what I've gathered from the mons in the viability rankings
Great Tusk
252 Atk Choice Band Tera Fighting Great Tusk Close Combat vs. 252 HP / 252+ Def Ting-Lu: 488-576 (94.9 - 112%) -- 68.8% chance to OHKO
This is one of those that isn't ideal in any circumstances because Tusk needs to deal with a lot of things right now including that stupid, living incarnation of cancer itself, Kingambit
Iron Valiant
+2 252 Atk Iron Valiant Close Combat vs. 252 HP / 252+ Def Ting-Lu: 482-570 (93.7 - 110.8%) -- 62.5% chance to OHKO
This one is not that bad since all you need to do is click sd, which many physical sets do anyway
Greninja
+1 252 SpA Life Orb Tera Water Greninja Hydro Pump vs. 252 HP / 252+ SpD Vessel of Ruin Ting-Lu: 499-588 (97 - 114.3%) -- 81.3% chance to OHKO
+1 252 SpA Life Orb Greninja Hydro Pump vs. 252 HP / 252+ SpD Vessel of Ruin Ting-Lu in Rain: 556-658 (108.1 - 128%) -- guaranteed OHKO
Once more, not so ideal because this requires battle bond to have activated. Before that, I don't think Greninja ever one shots even with specs rain hydro miss
Walking Wake
244+ SpA Choice Specs Tera Water Walking Wake Hydro Steam vs. 252 HP / 252+ SpD Vessel of Ruin Ting-Lu in Rain: 520-616 (101.1 - 119.8%) -- guaranteed OHKO
This one I'm not so sure how ideal this is
Azumarill
+6 252+ Atk Huge Power Azumarill Liquidation vs. 252 HP / 252+ Def Ting-Lu: 830-980 (161.4 - 190.6%) -- guaranteed OHKO
This one, I don't think this is ideal since Azumarill has mostly become to check Baxcalibur. I guess this has uses from time to time but I personally have not seen it much
Basculegion
252+ Atk Choice Band Tera Water Basculegion Wave Crash vs. 252 HP / 252+ Def Ting-Lu: 480-568 (93.3 - 110.5%) -- 62.5% chance to OHKO
252+ Atk Choice Band Basculegion Wave Crash vs. 252 HP / 252+ Def Ting-Lu in Rain: 542-638 (105.4 - 124.1%) -- guaranteed OHKO
Rillaboom
252+ Atk Choice Band Rillaboom Wood Hammer vs. 252 HP / 252+ Def Ting-Lu in Grassy Terrain: 504-594 (98 - 115.5%) -- 87.5% chance to OHKO
Breloom
252+ Atk Choice Band Tera Fighting Breloom Close Combat vs. 252 HP / 252+ Def Ting-Lu: 532-628 (103.5 - 122.1%) -- guaranteed OHKO
Iron Hands
200+ Atk Choice Band Tera Fighting Iron Hands Close Combat vs. 252 HP / 252+ Def Ting-Lu: 544-640 (105.8 - 124.5%) -- guaranteed OHKO
252 Atk Choice Band Tera Fighting Great Tusk Close Combat vs. 252 HP / 252+ Def Ting-Lu: 488-576 (94.9 - 112%) -- 68.8% chance to OHKO
For the rest of them, they are absolutely not ideal at all. They're in the B ranks so they're not that common