Whoops! My bad. Well me missing Gallade is inexcusable, though I can at least somewhat make up with saying maybe Beedrill and Kabutops and say they should probably learn via level up?... Yeah, I messed up
EDIT: Wait! I found one! Seviper has a blade tail yet it doesn't learn Swords Dance... also I notice a lot of Pokemon who don't really have a sword/blade/claw/sharp-edge body part can learn it via TM.
Also I need to make another addendum: now thinking about it, the reason Oddish family learns it is probably because Bellossom is based on dancing. To make it up, here's two for everyone's favorite power-up moves, Shell Smash & Quiver Dance:
Shell Smash:
1. First, the idea of Shell Smash is that the Pokemon is giving up its defensive shell to increase its attack power and speed. And this make senses for all Pokemon who learn it by leveling up. Of course this has created one odd circumstance: Clamperl. It makes sense for Clamperl (even though that'll leave it as just a face orb but I digress), but then Clamperl is one of those Pokemon with evolutions that don't make sense as it evolves into two eel Pokemon: Huntail and Gorebyss. How does Shell Smash work for them? Huntail has no shells unless you count its vaguely shell-shaped fins and Gorebyss shells aren't defending it like the move concept is about... and it's also using its shells as a bra... I'll leave you with your own conclusions.
2. Pokemon with a shell that don't learn Shell Smash (and this time I checked): Squirtle family, Golem, Slowbro, Lapras, Slowking, Pineco family, Aron family, Anorith family, Turtwig family, Samurott, Ferroseed family, & Bergmite family.
Also the cocoon Pokemon (Metapod, Kakuna, Pupitar, Silcoon, Cascoon, Shelgon, Swadloon(?), Whirlipede, Spewpa(?)) also technically have shells. Also Togepi is still covered by its egg shell (and I suppose this also goes for Exeggecute). And if you count seeds as having shells that goes for Sunkern and Seedot. And let's not even go into all the bugs who's body is considered to be a shell... and all the Pokemon who you can sort of say have a shell-like covering like with Glalie, the Burmy family, Escavalier...
Quiver Dance:
1. It's Japanese name is "Butterfly Dance", yet non-butterfly Pokemon can learn it like Venomoth, Dustox, Masquerain, Mothim, & Volcarona. "Well they're moths, they're close enough to Butterflies". Okay, then how do you explain Lilligant (yes it has a dancing theme, but so does Bellossom yet it doesn't get Quiver Dance)?
2. But hey, if Lilligant is an example of a fairy-like creature getting Quiver Dance maybe other winged faeries can get it too like Celebi & Togetic. Now I'd even say it wouldn't be that far fetch to maybe spread it to other flying Bug-types, but I think I'll stop right here.