This site contains a full walkthrough of cerulean cave for both fire red and leaf green versions of pokémon, including a map of all floors with helpful notes to show you where ladders lead.
http://www.psypokes.com/lgfr/dungeon.php
It is in Cerulean Cave. It is on the bottom floor of the cave! :P
You can find ditto in cerulean cave.
You can find Mewtwo in the Cerulean Cave.
You can find pretty strong ones in cerulean cave.
Yes in Firered/Leafgreen and Heartgold/Soulsilver
He's found in Cerulean Cave at lvl 58 and 67.
Yes, you can. You will find it at the same place as in FireRed and LeafGreen: In the Cerulean Cave in Kanto
go to cerulean cave after you beat the elite four and help celio fix his machine on those islands. you go into cerulean cave work your way through that and mewtwo is in there
there is no cerulean cave in ruby
you can find mewtwo in cerulean cave, just make sure you have a master ball it will make it so much easier to catch him.
There not in cerulean cave.
Go to Cerulean Cave after beating the Elite Four and then walk around in the cave and there are a whole bunch of level 52s there. Other places to find Primeape in FireRed and LeafGreen are Route 23 and Victory Road.