Go to canalve city n the little blue house below the move deleter lives there

Its in the game but it travels so its kind of hard to catch

The best way is to keep tracking it down and weaken it until its easy to catch and use mean look to keep it in the match longer if you like timer balls

First you need to get the national pokedex and them go to Erthern city and the house where nobody lived before go into it and pro. Oak should be there and he'll tell you that the birds are in Shinnoh

Timer balls are in the pokemon league market

Well you have to have past the distortion world and then go challenge the other gym leaders after that you have to meet one of the elite four that tells you to beat teh 8 gym leader

Mew two is in the curelean cave and mew you have to get him by an event