Pokemon that learn Night Slash through breeding (Egg Moves) in X and Y are:
Sandshrew
Farfetch'd
Scyther
Gligar
Teddiursa
Torchic
Slakoth
Nincada
Zangoose
Seviper
Shinx
Skorupi
The Pokemon that can learn the Night Slash attack via breeding are Sandshrew, Mankey, Sandslash, Primeape, Scyther, Scizor, Farfetch'd, Ursaring, Gligar, Gliscor, Teddiursa, Ariados, Spinarak, Blaziken, Torchic, Combusken, Vigoroth, Slakoth, Slaking, Ninjask, Nincada, Zangoose, Shedinja, Seviper, Luxray, Shinx, Luxio, Drapion, Skorupi, Dewott, Oshawott, Samurott, Tranquill, Pidove, Unfezant, Crustle, Dwebble, Fraxure, Haxorus, Axew, Heatmor, Beartic and Cubchoo.
Sceptile, to my knowledge, is incapable of learning Night Slash.
I think night slash because more Pokemon can learn slash but few can learn night slash if it weren't a TM
See related links section.
95
Shadow Ball
Sources say... Night Slash...
there is no night slash in diamond
First, do not evolve your sneasel, second, find a heart scale, third go to the move relearner's house. Give him the heart scale and select your sneasel to relearn night slash
In Pokémon Black and Pokémon White, the moves that Reshiram is capable of learning would include ones such as Dragon Rage, Fire Fang, Ancientpower, Imprison, Slash, Extrasensory, Slash, Dragonbreath, Flamethrower, Hyper Voice, Fire Blast, Fire Blast, Outrage, Crunch as well as its signature attacks of Fusion Flare and Blue Flare.
Absol learns the move Night Slash at level 41. Absol also learns the Psychic type version of Night Slash called Psycho Cut at level 47.
In Pokémon Pearl, the moves that Garchomp are capable of learning via level up are ones such as Slash, Sandstorm, Take Down, Sand Tomb, Tackle, Fire Fang, Dragon Rage, Sand Attack, Dragon Claw, Crunch, Dig and Dragon Rush.
Crunch-80 chance at lowering defense Night Slash-70 high critical hit chance