Darrel J. Delfin is a Los Angeles based voice actor for the English dub of Pokémon Masters EX. He is credited as simply "Darrel Delfin".
His official website is:
https://www.darreljdelfin.com/
Team Magma Grunt Pokémon Masters EX Announcement Tweet
On July 29th, 2022, Darrel
announced on Twitter that he was the voice of the Team Magma Grunt in Pokémon Masters EX.
"Our power is overflowing... Like MAGMA!" Thrilled to join the Pokémon universe as the Team Magma Grunt in #PokémonMastersEX. Hope you enjoy the new Hoenn Chapter of the Villain Arc!