I have a pen. (Common, standard) I’ve got a pen. (Same meaning, common, easier to say, more casual. Not ‘I have got a pen’) I got a pen. (If said to mean ‘I have a pen’, it’s weak and very casual but you will hear it. It’s okay if said to mean something like - I received/retrieved a pen) Does anyone have anything to write with? Yes, I’ve got a pen. Yes, I have a pen in my purse. Yeah, I got a pen around here somewhere. (Lower register of speech) I got a pen for Christmas. (I received it as a present.) I got a pen from the desk. (I went over to the desk, picked up the pen, and brought it back.)

Hi Rajaramesh, Just a fun fact, in the U.S. we almost never say "I have got." We would say "I have a pen," or "I got a pen." "I have a pen," means there is a pen in my possession. "I got a pen," means I obtained a pen somehow.

I have a pen is correct, when you say “i have got” you’re implying that you have received a pen as opposed to saying that it is something you have. i hope that helps!!