Mt.Moon
You can only using a Nintendo mystery gift.
you cant catch entei on Pokemon pearl. entei is a johto Pokemon and Pokemon pearl is a sinnoh game. the only way to getentei is to trade it over from another game games compatible are Pokemon diamond, Pokemon platinum, Pokemon soulsilver and Pokemon heartgold. the last two i am sure you can get entei. (i have seen it in the wild)
The only legitimate way to obtain Celebi and Mew is through a Nintendo event. In FireRed and LeafGreen you will need an event-only item to travel to the last two islands where you can catch those Pokemon
you can't Mew and Mewtwo are two completely different pokemon. Mewtwo is accually a clone of the original Mew. So... no, you can't evolve Mew into Mewtwo.
You can't catch it at Pokemon Pearl, you'll have to Transfer it from LeafGreen/FireRed or trade it with SoulSilver/HeartGold
you have to migrate at pal park near sandgem town == ==
You cannot catch Mew in "Pokémon Ruby."or you can get mew-two in fire red or leaf green.
Mt.Moon
You can't catch Mewtwo in-game in Pokemon Diamond.
You wont be able not catch a Mew natively in the two brandnew Pokemon games wich are Dimond and Pearl. But still, there is anofer way! A few months ago Toys-R-Us had a Mew give away deal. Try there!
The Cerulean Cave
YOU JUST COItinue what your doing
sadly,no
You catch Mew-Two
you cant without an ar
Mew and Mewtwo are not found anywhere in the Sinnoh region.