HMs and TMs are vital parts of creating the perfect moveset for a Pokemon to use in battle.
HMs are often used outside of battle to help traverse the region of the Pokemon game. TMs are learned and used to duke it out against the partners of other trainers.
Believe it or not, there are a lot of Pokemon that cannot learn moves via HM or TM. Even if they can learn the move from leveling up, they are not compatible with the Hidden Machine or Technical Machine in at least one Generation.
Note: This article is subjective and reflects the opinion of the writer.
Top 5 Pokemon who can't learn any HM or TMs
#5 - Wobbufett
Strangely, Wobbufett is a fully evolved Pokemon that cannot learn any TMs or HMs. Prior to Generation VI, Wobbufett has no TMs or HMs available to learn. Gen VI sees it finally learn Safeguard, which is TM20. As a decently strong Psychic-type, it is incredibly odd that Wobbufett was once unable to learn any TMs or HMs.
#4 - Smeargle
Smeargle is a Pokemon that currently learns no moves by TM or HM. It has not been given any to its learnset up to this point. Smeargle is the Painter Pokemon and only learns the move Sketch. Sketch can target any Pokemon on the battlefield and allow Smeargle to permanently learn the last move used. It is ironic that a Pokemon who can learn almost any move can't actually be taught any moves.
#3 - Cosmog/Cosmoem
Cosmog evolves into Cosmoem, which then evolves into Solgaleo in Sun, Ultra Sun, and Sword or Lunala in Moon, Ultra Moon, and Shield. It can evolve into two extremely powerful Legendary Pokemon. By leveling up, it can learn a few Psychic-type moves, but nothing else. It is left waiting for a full evolution in order to put any TMs or HMs to use.
#2 - Magikarp
Magikarp can actually learn Bounce and Hydro Pump in Generation VIII. Prior to that, however, Magikarp was one of many Pokemon that could not learn a move via TM or HM. Everyone knows that Magikarp evolves into the incredibly powerful Gyarados. It is just wild to know that Magikarp can't be taught any moves prior to Gen VIII in order to help itself level up and achieve that evolution.
#1 - Ditto
Ditto falls into the same category of irony that Smeargle does. Ditto can essentially learn every move in the history of Pokemon. It can do this through its signature Transform maneuver. That allows Ditto to transform into its opponent, copying its moves, its abilities, its appearance, and much more. Even with that incredible power, Ditto learns a big fat zero in terms of other moves, either by leveling or through a TM/HM.