It has a very good move pool. Zen Headbutt and Meteor Mash are two great stab moves with good secondary effects. The other 2 moves you want are for coverage. You can run earthquake for other steel types (mainly magnezones that want to trap you), or you can run thunderpunch to hit water types and flying types really hard. Hammer arm is also a great move that covers your dark weakness as well as hits steel types hard as well if you don't want to run earthquake. Ice punch is not really used in the PRO meta but it can catch dragonites and gliscors if they aren't expecting it as well. Also he gets priority in bullet punch which can be very helpful to pick off weakened pokemon or hit togekiss really hard before it can roost.
My suggestion though:
Zen Headbutt
Meteor Mash
Earthquake
Thunder Punch/Ice Punch.
so I remove hammer arm then place a ice punch or thunder punch
anyway..i see on trade furom a metagross it train in atk252 hp 250 def8...