A good question

[CrazyTrainer]

Hey can anybody answer this. Why didn't they make a light type. One for the black and white games. So that the white dragon is light black dragon is dark. Also ghost and dark have nothing super effective to it.

[Galdr]

I believe they'll make a light type for Gen VI, if possible.
Though, it would make sense for Reshiram to be the Light/Dragon type and Zekrom could be Dark/Dragon or Ghost/Dragon. However, Giratina is already the Ghost/Dragon and Sazandora is already the Dark/Dragon. They needed to have a different typing to both dragon mascots, so they possibly had to choose between two other non-used types for the dragon dual-typing.

Though, yes the Light type for Reshiram would have been a good idea, as it would complete the whole Yin & Yang they got going on. However, they choose Fire/Dragon for Reshiram and Electric/Dragon for Zekrom.

This is all opinion, though I hope it satisfies as an answer~

[Viva la Gofre]

It's highly unlikely any new types will ever be added. Steel and Dark were added in generation 2 to balance the game, in particular to lessen the domination on Psychic types and (to a lesser extent) Dragon Types. Neither of the types were resisted by any other types, other than Psychic resisting itself, which led to the game being very unbalanced. Dark and Steel lessened this to the extent that they became manageable, and left us with a balanced game. There's literally no reason to add new types, and doing so would risk once again unbalancing the game.

[Leki Fenrir]

And Dark-types take super effective damage to Bug and Fighting.
Ghost-types take super effective damage to Dark and Ghost.

And my opinion on the Light-type is that it would be nearly redundant with Electric. Added to the fact a lot of reflective sounding moves are attributed to Steel, it just seems like it'd be a lot of work to squeeze in a new Type this late in the game.

[Teddiursa of the Sky]

We have been over this before. Psychic-type Pokemon are considered the light side of the creep triangle. This has been demonstrated many a time before. For example, the episode where the giant Alakazam and giant Gengar have an epic fight when released from their tiny ancient Pokeballs. This is pretty interesting, as there is no "light-type."

Fighting, Bug, Steel >SUPER EFFECTIVE> Dark

Ghost, Psychic, Dark >SUPER EFFECTIVE> Ghost

[CrazyTrainer]

I was talking about dark and ghost together is unstoppable.

[Viva la Gofre]

Originally Posted by CrazyTrainer

I was talking about dark and ghost together is unstoppable.

Having no weaknesses doesn't make them unstoppable, it makes slightly less easy to crush than other things. Spiritomb and Sableye are both extremely easy to deal with because they have very few decent resistances, meaning they can easily be muscled over by a decent attacker.

[Etymology]

I doubt the Light type will ever be created, which is good in my opinion. The last chance for its creation was definately with Reshiram and Zekrom. Everyone thought Reshiram would be a 'Light' type. People were disappointed when it wasn't.

And basically, Psychic = Light anyway. Why does everyone insist on a new type so bad?

[shadowinfernape]

I don't think they aren't gonna add any new type.Before Gen 5 I thought that they were gonna add it but they did'nt ):

[Teddiursa of the Sky]

I never thought, and I knew that they would not add another type. And the fact of the matter is they won't, and we have already discussed this before Black and White were even released in Japan.