Google is your friend.
Hex editor
Relative Search (not needed always since many games just use Shift-JIS or Ascii)
Tilemolester
Emulator (with debug features if you want sthg deep and advanced as figuring out compression or if you want to modify the way the game behaves instead of just replacing text/graphic/music.... but then you need to know ASM)
Minimal grasp of the language the game is in (ie JP / Eng / KR / ...)
Some tools exist for well known console specific formats (for example in DS games there is Tinke and Crystaltile2 , you can refer to the sticky threas for more, and good old hex editor)
Most translators code their tools themselves (programming needed) but often they just automate the process he would have done with the above (or decompress the file toa state where he can use the above methods)
And Google.
............. However if you are fluent in the source language you can join an existing team as a translator.
People fluent in Japanese and Korean are especially welcome here.