To be specific, the Mew and Phione be in a Cherish ball, their locations will be "apparently had a fateful encounter a Lovely Place", the OT will be Hayley, their ID will be 01001, and the Mew will have the following moveset:
Mew lv. 50 @ none
Random Nature
Synchronize
~Synthesis
~Return
~Teleport
~Hypnosis
This is a special Mew since no other Mew can have Synthesis, Teleport, or Hypnosis normally. The Phione has no special moves other than Grass Knot. To get the Phione, deposit 250 Pokemon and trade for a Leafeon. To get the Mew, deposit 999 Pokemon and trade for an egg.
The other Pokemon she may trade you are include Pikachu, Eevee, Shellos (East Sea), Croagunk, Finneon, Wynaut, Pachirisu, Aerodactyl, Lickitung, Wailmer, Combee (female), Staravia, Yanma, Snowver, Shroomish, Ponyta, Buneary, Miltank, Tangela, and Vulpix. Each will have a OT of Hayley, and an ID of 01001. Most of them will also have some kind of move taught to them that they wouldn't normally know being caught from the wild (TMs or egg moves) and will all be holding the Super Effective Reduction Berries except for Lickitung and Miltank who will be holding TM44 Rest and MooMoo Milk respectively.