Are there any pokemon that can learn a one hit ko and a move that ensures a hit? If so, which one, and which moves?

Question

Self Explanitory

Answer 1

As of Generation IX, Smeargle learns Lock-On/Mind Reader and all OHKO Moves, Poliwhirl and its evolutions learn Fissure and Mind Reader, and Articuno learns Sheer Cold and Mind Reader.

Answer 2

Articuno with Mind Reader and Sheer Cold.

Smeargle with Lock On/Mind Reader and Sheer Cold/Horn Drill/Guillotine/Fissure

Answer 3

Articuno
Mind Reader
Sheer Cold