Chazz never uses L & D Dragon in the anime. Strangely enough, the GX anime was being released before the manga. There are even little asides between chapters in GX volumes that talk about how the artist got the job, and didn't want it to be an "animanga." So in Yugioh canon (such as it is) GX manga doesn't really exist.
For one, just because it was used in the manga doesn't make it a major card. Axel uses it, but, assuming he gets added, it's not like Electro's gonna get an animation, and he won't be a level up reward. I doubt Electro will even get a voice clip.
And your point is what exactly? There's a lot of voice lines. The newer characters (GX characters, and a few newer DM characters like Arkana) have a lot of lines for cards that obviously won't be included for a long time, if ever. Jesse has one for Crystal Abundance, and a lot of anime-only cards. Arkana has a line for Pandora's Jewelry Box, a Pendulum Monster.
I used to just think that voice lines meant that a card would come, but now I think that they probably just had the actors/actresses record a lot of stuff just to have the lines ready in case certain cards get released.
actually, I remember a version of the anime where Chazz DID use L&D Dragon, but for some reason, that part of the anime can't be found. It's the same thing with the planet card series (Terra Firma is a part of it.) There was an entire story arc with the planet card series, but when I looked back to re-watched the series, it wasn't there. My guess is because it was produced by 4KIDS
Light and Darkness Dragon has never appeared in the anime, used by Chazz or anyone else.
The manga are usually (ignoring the original) written late into/after the series they're based on concludes, so including cards that debut there is usually impossible. (And most characters have radically different decks in the manga, anyway, so their cards would have no reason to show up in the anime.)
Doesn't mean they CAN'T be given by characters in Duel Links, of course. It takes inspiration from every source it can, and we've had several manga cards make it into LD's cardpools in one way or another. Yugi's Union Attack, Yami Yugi's Van'Dalgyon, Syrus's Carrieroid and Akiza's Rosaria are examples of this. It's even more common with the "Super duelist" events. Bastion's is a good example.