Uhm and what about a shiny legendary?Anyways I don't even know what GTS is.Also what is a good guide for what pokemons are worth?
First of all, GTS is the Global Trade Station. You can access it from the Player Search System (right next to Super Training or Pokémon-Amie) on your lower 3DS screen in X and Y. At the GTS, you can either ask for a Pokémon and offer a Pokémon in return, or you can search for Pokémon other people have offered, and see what they want in return for it. It's global trading made simple.
Or, well, "simple". Keep in mind that people can ask for
any Pokémon when offering one of their own. You will find a LOT of people offering a Caterpie and wanting a Zekrom or something like that in return. Likewise, if you want a Zekrom of your own, you better offer something really good for it. Nobody in their right state of mind will ever give away their Zekrom in exchange for a lvl. 23 Mightyena.
However, there is no currency system in place. Technically speaking, it's not impossible that somebody will trade a Mew for a Magikarp. The only thing ever restricting trades like that, are the wants and whims of the players themselves. In a sense, the laws of supply and demand rule the GTS. There is no "right" or "wrong" price to ask for on the GTS. Only a lot of stupid (and I mean
loads of stupid - people offering Scatterbug and asking for Shiny Articuno is the norm, not the exception). The world of Pokémon is quite chock-full of eight-year-olds who think they can get gold in exchange for pebbles.
There is something throwing this chaotic "market" off the rails, though: The GTS' Hack Check isn't very good. Occasionally, there will be people using hacks to create shiny legendary Pokémon and put on the GTS just for the lulz.
Anyway, my point is: If you want a shiny legendary or something, you pretty much have to offer something similar in return. Or hope people will be nice. Here at Smogon, there are
threads over in Wi-Fi where you can make requests, too, but they generally frown upon people asking for super-rare stuff without offering something good in return. Also, making a new thread asking for something is a cardinal sin, so don't do that.
If you've got something "good" you want to trade away, and just want to know what you'd get for it, my best tip is to put in on the GTS and wait for a day or so. Just use common sense, and you'll be fine. Generally, people are looking for stuff like:
- Version exclusive Pokémon (check Serebii for lists)
- Starters
- Eevee
- Fossils
- First stage pseudo-legendary Pokémon
- Pokémon that evolve upon trading
These Pokémon are not hard to get, and you're likely to get something similar in return for them.
Other than that, again, common sense.
Also, once you get PokéRus and know how to deal with it, it'll be all over your PC, so don't ever let anybody fool you into thinking you should trade away your version exclusive legendary in return for a Pokérus Magikarp. Just use Wonder Trade a lot, and you'll end up with Pokérus pretty soon anyway.