Gohan attacks Frieza with a Masenko Blast in Episode 83 "Another Transformation?", because Frieza is about to kill Piccolo.
Episode 85 - Gohan Returns
freiza then gohan comes in freiza transforms then he kills vegeta then goku comes and pwns him then ss1 goku vs freiza
yes but it is only for trunks krillin freiza gohan and vegta
when gohan has his dream he will go out window and go to save point first then go right from save point then open lv 1 door then go right then you will see freiza disguised as goku then he will undisguise himself then you will have to fight freiza. Freizas second appearance is when you get to the end of northern high lands then there is a cutscene when trunks kills freiza then king cold and that is the last of freiza
Gohan goes mystic in Episode 247: Unlucky Break
They actually met in high school in the episode '' Gohan goes to high school ''
episode 176
episode 166
The answer to your question is Episode 185
episode 156
In the Original Series Gohan kills him in Episode 176 In the Remastered Series Gohan Kills him in episode 191
Dbz episode 1