How do you unlock heihachi mishima?

To unlock Heihachi Mishima in tekken 4 play with a character and when you unlock new characters play with them, keep doing this till you get all the characters and heihachi will be there. But in tekken 5 you just have to keep on playing story battle until you get all the characters.

Also you cant get the boss character in tekken 5, Jinpachi Mishima you can only get him when you play tekken 5 in PS3.

Hope this helps!