How to get legendary pokemon on pokemon y
Hello, lynxgamer911. In Pokemon Y, Yveltal can be encountered in Team Flare's secret lair and caught there. Xerneas is unavailable to Pokemon Y. To capture Zygarde, you must first defeat the Elite 4 and Champion, then go to Terminus Cave, and traverse it until you get to the deepest area. You will eventually find it there. You can also capture one of the legendary birds (Articuno, Zapdos, or Moltres), depending on who you picked as a starter. You will encounter one of them in tall grass/cave/water after the Elite four. You will then need to encounter it around a dozen times more (you may be able to use the Pokedex to find out where it is, but it changes position regularly). After encountering them around a dozen times, they will go to the Sea Spirit's Den, at Azure Bay. You will be able to battle and catch them there. To capture Mewtwo, you will need to go to the cave in Pokemon Village after beating the Elite 4. It will drop its Mega Stone, Mewtwonite Y, after capture or defeat.
You may only catch four legendary Pokemon in Pokemon Y. To obtain the others, you will need to trade with other games.