Softball bats in Baseball ?
 

hi,
are softball bats allowed to use in a baseball game (pro rules) ?

Only if they meet the requirements under the rules and most (if not all) softball bats do not.

Rule 1.10 (a) The bat shall be a smooth, round stick not more than 2¾ inches in diameter at the thickest part and not more than 42 inches in length. The bat shall be one piece of solid wood.

Some leagues play under OBR rules and modify rule 1.10 to allow non-wood bats. Most of those league require non-wood bats to be BESR certified. Softball bats (as far as I know) are not tested and would not meet the basic BESR certification requirements (2 5/8" diameter barrel and no more than a -3 drop length to weight).

One of the "some leagues" is Little League and they do not allow SB bats in a BB game.