while playing fallout tactics i talked to a mutant in one of the mission and said the thing that attacked him didnt feal pain and said he used to feal like that. so do super mutants feal pain

Well, yeah, I don't remember God's dialogue 100% but he said that Dog is inflicting pain upon himself to quiet down God.
So if he doesn't feel pain then it shouldn't have been able to quiet God down.

Of course, they're a Nightkin, so they "might" function differently, but I highly doubt that.
I think that in the old games when you shoot Unity members in the eyes the info-box says stuff like "You critically hit Super Mutant in the eyes for 34 damage inflicting heavy pain."
So I think they do.
Maybe the mutant in Tactics is different though.

the mutants in tactics are the marisopa mutants cause some mutant said somthing about the master

Well yeah I know that they're mariposa mutants but not all super mutants mutate "the exact same way".
So he might have mutated away his nerve system or whatever, meaning he doesn't feel any pain.
Or maybe some part of his brain is faulty and he's felt artificial pain in him all the time meaning that real pain doesn't affect him.

Or maybe he's just crazy or boastful. Either way, Marcus always says "I am NOT a merry mutant" if someone shoots him =)

Yes, they do. Atleast in Fallout they did.