Oversized Tee's - This is my favourite shirt for any occasion.
Sizing depends on how you want the shirt to fit... I (Regan) wear the 4xl at 290-300lbs because I like the way in hangs off my shoulders for that oversized fit! I could get away with wearing a 2xl or a 3xl but that is my personal preference!
I would suggest following this sizing chart if you want it to fit oversized but you can always go up a size if you want it bigger!
180 and under size Large
200 under size XL
220 under size XXL
250 under size 3XL
250+ Size 4XL