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,

Lock On + OHKO Move

/nds fissure, lock on
Smeargle
/nds guillotine, lock on
Smeargle
/nds horn drill, lock on
Smeargle
/nds sheer cold, lock on
Smeargle

Mind Reader + OHKO Move

/nds fissure, mind reader:
Politoed, Poliwhirl, Poliwrath, Smeargle
/nds guillotine, mind reader
Smeargle
/nds horn drill, mind reader
Smeargle
/nds sheer cold, mind reader:
Articuno, Smeargle

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