I believe Ceruledge getting Dragon Claw is rooted in the fact that it is distinctly driven by dark energy and emotions of malice.
Dragon as a type embodies use of the energy of nature but uses such energy in a parasitic relationship with nature and often driven by rage and negative emotion. In essence, it is the use of Dragon as a type driven by negative energy, which is in contrast to its antithesis, Fairy, which is in turn a type also driven by nature but uses such energy in a more symbiotic relationship with nature and is driven by more positive energy, relying on more positive emotion in doing so.
Dragon Claw is basically the most generic "Dragon attack", but as a Dragon move the characteristics of the Dragon type I outlined are highlighted by the other Dragon attacks. Dragon Rush is labeled as an attack that is a full blown body slam driven by overwhelming menace. Outrage is a move where the Pokemon goes on a violent rampage uncontrollably for 2-3 turns before calming down and then becoming dizzy afterward. Dragon Breath and Dragon Rage are breath-based attacks that have abnormal traits (former induces paralysis while the latter is a weak fixed damage attack). Dragon Pulse is a shock wave from the user's gaping mouth. Note: shock wave. Draco Meteor is a violent meteor shower from the skies that relies on the user's special energy and expends much of it in doing so. You get the point.
Chesnaught is a starter and is in the "cool, tough looking" category so I suppose they thought it would work there.
That said, however, Barbaracle distinctly works because its Japanese name has the word "death" in it while its English name partially derives from the word "barbarian", which suggest a nasty and menacing beast. Pangoro is driven by anger a lot of the time and is very rough-mannered and short-tempered. Bewear is also incredibly dangerous. You get the drill.
In a sense Dragon Claw is looked at by the characteristic of the Dragon type being the "uses the power of nature driven by malice and destruction" type in terms of what makes Dragon-type moves, well, Dragon-type.
Contrast that with Fairy-type's corresponding generic "Fairy attack", which is arguably Dazzling Gleam: many Fairy-types and Psychic-types learn it, but many Pokemon such as Roserade, Arboliva, Manaphy, and Audino learn it, because they are more in tune with nature and some of them like Audino and Arboliva are more benevolent, and in general is using special light energy in a way that is symbiotic with nature, acting in tandem with it.
It is much like how other Fairy-type moves can in many ways be antithetical to Dragon-type. Play Rough is a physical attack in which the user roughouses the opponent: the opponent doesn't find it fun, but the user does, acting on playfulness and mischief. Moonblast draws power from the moon in a way that it borrows it (whereas Draco Meteor arguably involves the user stealing energy from meteors). Disarming Voice does emotional damage to the opponent, not direct damage really. Fairy Wind is a generic wind attack with no other effects. Nature's Madness directly uses the power of nature synergetically with its user. And so on.
I went on a bit of a tangent there, but hopefully you get the point. I brought in Fairy-type as a direct contrast to further emphasize the specific characteristic of Dragon-type that likely determines who gets to learn Dragon Claw, because I feel it's important to know exactly what the Dragon-type's deal really is about (speaking as a Dragon-type enthusiast myself).
With Dragon Claw specifically I feel some of the standouts are cases where they are driven by some form of menace or other negative energy and unleash it in a special claw slash. Ceruledge in particular is basically the embodiment of malice and hatred and thus uses Dragon Claw by harnessing the energy of nature but channeling it through the malice in its heart I feel.
Dragon as a type embodies use of the energy of nature but uses such energy in a parasitic relationship with nature and often driven by rage and negative emotion. In essence, it is the use of Dragon as a type driven by negative energy, which is in contrast to its antithesis, Fairy, which is in turn a type also driven by nature but uses such energy in a more symbiotic relationship with nature and is driven by more positive energy, relying on more positive emotion in doing so.
Dragon Claw is basically the most generic "Dragon attack", but as a Dragon move the characteristics of the Dragon type I outlined are highlighted by the other Dragon attacks. Dragon Rush is labeled as an attack that is a full blown body slam driven by overwhelming menace. Outrage is a move where the Pokemon goes on a violent rampage uncontrollably for 2-3 turns before calming down and then becoming dizzy afterward. Dragon Breath and Dragon Rage are breath-based attacks that have abnormal traits (former induces paralysis while the latter is a weak fixed damage attack). Dragon Pulse is a shock wave from the user's gaping mouth. Note: shock wave. Draco Meteor is a violent meteor shower from the skies that relies on the user's special energy and expends much of it in doing so. You get the point.
Chesnaught is a starter and is in the "cool, tough looking" category so I suppose they thought it would work there.
That said, however, Barbaracle distinctly works because its Japanese name has the word "death" in it while its English name partially derives from the word "barbarian", which suggest a nasty and menacing beast. Pangoro is driven by anger a lot of the time and is very rough-mannered and short-tempered. Bewear is also incredibly dangerous. You get the drill.
In a sense Dragon Claw is looked at by the characteristic of the Dragon type being the "uses the power of nature driven by malice and destruction" type in terms of what makes Dragon-type moves, well, Dragon-type.
Contrast that with Fairy-type's corresponding generic "Fairy attack", which is arguably Dazzling Gleam: many Fairy-types and Psychic-types learn it, but many Pokemon such as Roserade, Arboliva, Manaphy, and Audino learn it, because they are more in tune with nature and some of them like Audino and Arboliva are more benevolent, and in general is using special light energy in a way that is symbiotic with nature, acting in tandem with it.
It is much like how other Fairy-type moves can in many ways be antithetical to Dragon-type. Play Rough is a physical attack in which the user roughouses the opponent: the opponent doesn't find it fun, but the user does, acting on playfulness and mischief. Moonblast draws power from the moon in a way that it borrows it (whereas Draco Meteor arguably involves the user stealing energy from meteors). Disarming Voice does emotional damage to the opponent, not direct damage really. Fairy Wind is a generic wind attack with no other effects. Nature's Madness directly uses the power of nature synergetically with its user. And so on.
I went on a bit of a tangent there, but hopefully you get the point. I brought in Fairy-type as a direct contrast to further emphasize the specific characteristic of Dragon-type that likely determines who gets to learn Dragon Claw, because I feel it's important to know exactly what the Dragon-type's deal really is about (speaking as a Dragon-type enthusiast myself).
With Dragon Claw specifically I feel some of the standouts are cases where they are driven by some form of menace or other negative energy and unleash it in a special claw slash. Ceruledge in particular is basically the embodiment of malice and hatred and thus uses Dragon Claw by harnessing the energy of nature but channeling it through the malice in its heart I feel.