Ranger Mason is the Character of the Day in Mother of All Battles and is the ranger in charge of the Mt. Silver Pokémon Preserve, the same preserve Ash's Larvitar was stolen from.
After meeting Ash and company, she teamed up with them to stop any more poaching in the preserve. When the poachers were defeated by Larvitar's mother, Tyranitar, Mason captured the poachers and thanked Ash and friends before they departed for the Silver Conference.
Crawconaw is Mason's only known Pokémon. It was first seen riding on the back of her motorcycle when Mason came to help Ash and friends, who were under attack from the poachers. It later on teamed up with Ash's Pikachu to blast off Team Rocket before both of them were captured by the poachers. They were finally released when Tyranitar's Hyper Beam and Larvitar's Hidden Power sent the poachers blasting off. It was last seen saying goodbye with Mason.
This is the mother of the Larvitar Ash held on to temporarily. She appeared in Address Unown! in the dimension created by an Unown and Lavitar's memories. In the dimension, Tyranitar was seen fighting poachers, receiving a scar in the process, before Lavitar's egg was stolen by the poachers. She then appears in Mother of All Battles. She mistakenly assumes Ash and friends are poachers until Larvitar calms her down. But the poachers from Larvitar's memories appear and capture Tyranitar.
After freeing herself from their clutches, she teams up with Lavitar and blasts the poachers away with her Hyper Beam and Larvitar's Hidden Power. Soon after, she and Larvitar are reunited and bid goodbye to Ash and company.
Larvitar was entrusted to Ash by Professor Elm as an egg. After a rough hatching, where its shell was cold, it hatched but was afraid others, causing it to use Screech to drive them away or by freezing in fear. Slowly, it opened up to only Ash, but after helping it get past its emotional scars, it opened up to Ash's friends. After being reunited with its mother, it said goodbye to Ash and company.