Given the design of the series, as a whole, the concepts of mega evolutions, and, the new fairy type, attempting such in this current game, would be a bit problematic. However, given that, Nintendo/game freak/Pokémon have managed to establish the fairy type, as a new type, and, that, this site has succeeded in establishing a light type, and, that, both are separate entities, it's not to say, that, topaz couldn't use both, but, I think, at least for now, it should just remain as light only.

As for the fairy types, I think work should be made towards figuring out how each type will stack up against both light and fairy. But, given the amount of work going into it, I think these should just be side notes used within this site, at least, for the duration of the making of the game, so, that, too much time and energy aren't used up in trying to rebalance the actual game, and, rewriting everything about it.

Mega evos, do sound like they'd be fun, but, I really think they should be left to just certain ones. Like, I can't really see the need to have every Pokémon, with an extra evolution like that. But, I could see certain ones, such as the more typically, UU's being given the mega form. Things like, miltank, and, tauros, would do well with them, as well as others with only the single evos.

However, throwing in a Pokémon, that happens to be a fairy type, would be interesting, but, idt it should be a crucial part of the game. Making it like a sort of promo the way Nintendo did with things like mew, and celebii, it could work. But, again, a lot of work going into attempting to rebalancing the game.

Okay, so, yeah, everyone does seem to agree with not mixing the two types yet. I'd say, we could start on working out the stuff for the expansions/sequel, but, the first game needs to be completed first, so, it's definitely out the window for now.

I think, for the moment, some side notes could be made, such as, making a chart, with all the official types, plus, the light type, to kinda get an idea, of what may come out of it. Nothing more needs to be done in the meantime, but, I'm sure, there's still loads of work just going into the game as it is. I can only imagine that, certain things, such as the various hold items would also be thrown off a bit, and, should players begin to use them in battle, then, they'll be a rather crucial part to the game, making it more unstable in its current state.

Though, I must ask, is fairy the only new type within the canon universe? I could've sworn they added another one, but, idk entirely, given how far behind I am in the series o.o