After I tried the game repeatedly I still wont be able to get Special ending 3 and True ending, do I really need to pick "Resist" during the fight with Ocean Predator? so I can win the fight and proceed to the last 2 endings? Or the resist is not working either?
The final option requires 200 mental strength, but this is just for dramatic effect, so you cannot resist it.
The reason you cannot reach the true ending is probably because the guardian's brainwashing level is too high.
The brainwashing level is a hidden parameter, so you cannot check the numerical value, but you can judge it by the changes in the text on the status screen and in everyday conversations.