What is correct usage -- or correct semi-slang usage -- for verb in this sentence:
'he was a boy who got beat up often'
"He was a boy who was beaten often."
Based on Jim's point that beaten is ambiguous and John Lawler's comment about the requirement for slang usage, consider:
"He was a boy who was beaten up often."
If the requirements of slang mandate that got must be used in place of was, then so be it.