They played for the South team, which defeated the North 7-1.
Piatt started a rally in the sixth inning when he singled and scored a run. He finished the game with two hits in four at-bats.
Pupo pitched a scoreless ninth inning.
"It's great to see all three of those guys continue their success this summer and be recognized as all-stars," said Head Coach Al Corbeil.
"Cody will be one of the few players we have coming back, so I am pleased to see him doing so well against that competition. Matt and Jose had two great seasons for us here, and I was happy to see them have the opportunity to play for a pro-caliber coach like Kevin Davidson, who coaches the Winter Park Diamond Dawgs and played minor-league baseball for the Houston Astros. We wish them the best in the remainder of the summer."
Recognized by Baseball America as one of the top summer leagues in the United States, the Florida League lets college players play wood-bat baseball against top-level competition with the goal of preparing them for a career in professional baseball.