On August 16, 1986 — 1986 – Dale Holman, of the International League’s Richmond Braves becomes the first professional player ever to play for two teams in one game. The game was suspended because of rain on June 16th when he was in the lineup for Syracuse. By the time the game is completed today, Holman had been traded to Richmond and is in the lineup for the other side.

Source:
Baseball Reference August 16
National Pastime
Retro Sheet
Hall of Fame
SABR Games Project
Replay The Game