On today's MLB Immaculate Grid, there is a column for the San Diego Padres and a row for the Houston Astros. That means to complete today's grid, participants will need to know players that played for both teams.
Pitcher Jordan Lyles is a good answer to this prompt. The ace played for the Astros from 2011-13 as part of his major league journey. Then, in 2017 and 2018, he was a member of the Padres.
He was used by 0.3% of players at the time of writing.

MLB Immaculate Grid Answers August 16: Which other Astros players have also played for the Padres?
Here are more players who played for the Astros and Padres:
- Jason Castro (2010-2022 with HOU, 2020 with SDP)
- Wade LeBlanc (2008-2011 with SDP, 2013 with HOU)
- Pedro Martinez (1995 with HOU, 1993-1994 with SDP)
- Mark Melancon (2010-2011 with HOU, 2021 with SDP)
- Miguel Tejada (2008-2009 with HOU, 2010 with SDP)
Longtime Astros outfielder Jake Marisnick is another good answer. From 2014-19, he was in Houston. In 2021, he played a few games for the Padres, so he qualifies.

Be sure to visit Baseball Reference, as they have a full database that tells you every single player to suit up for both the Astros and Padres.