The only one I know Confagrigus because it has the word 'fag' in it.
They can't be traded due to the fact that some people may add some 'bad' words as a message in the name to the other trainer or to make fun of them.Eg. Probop- ass. And if you are wondering that some pokémon don't have those words and still they can't be traded because the game also checks other bad words in other languages.
Nintendo has always been a family-friendly company, so presumably these words are banned because kids might see them. This is especially a danger in modern games like Pokémon X and Y, which allow you to battle or trade with trainers all over the world through the internet. It’s a somewhat reasonable policy.
Actually getting a list of those Pokemon is really hard. I need some time to figure it out.
But this is the list I could get :
(Will keep updating)