Charla belongs to Liza, who maintains the Valley. When Ash and his friends were going through the Valley, they had the opportunity to meet Charla. Charla is Liza's only Pokémon, and her greatest partner, seeing as she travels with her to places outside the valley. Charla was also the only non-wild Pokémon in the valley when Ash and his friends met her.
Charla made a brief cameo appearance in Spell of the Unown with Liza and other Charizard from the Charicific Valley.
Charla was considered to be Liza's most trusted Pokémon out of the other Charizard in the Charicific Valley. During her debut episode, Charla had very little trouble in showing her flying skills in contrast to Ash's Charizard when they first arrived in the Valley. Charla started to bond with Ash's Charizard overtime during its stay at the Valley.
A † shows that the move was used recently, unless all moves fit this case or there are fewer than five known moves.
Trivia
Charla's Japanese name, リサ Lisa, comes from Charizard's Japanese name, リザードン Lizardon, and is also a girl's name that is similar to her Trainer's English name, Liza, and identical to her Trainer's English voice actress's first name. Likewise, her English name comes from a portmanteau of Carla, a girl's name, with Char, part of the name of all of the members of the Charmander evolution family.
In her first appearance, she was much larger than Ash's Charizard. The next time the two were seen, she was the same size as it. This probably due to the fact that Ash's Charizard has grown stronger (hence, a higher level and bigger size) over its 119-episode absence.
Related articles
For more information on this Pokémon's species, see Charizard.