Makoto

Arielle is a character of the day who appeared in The Whistle Stop (EP130).

Arielle has trained her six Ledyba since they were little. She looked after them when they were sick, and even slept with them in a hollow tree. By playing different notes on a whistle that has been passed down in her family for generations, Arielle trained her Pokémon to do obey her instructions.

She helps Mr. Douglas maintain his apple orchard and uses her Ledyba to pollinate the trees. Arielle's control over six Pokémon at once was likened by Misty to an army drill sergeant controlling a platoon of troops.

When Team Rocket stole her whistle, Arielle was initially uncertain that her Ledyba would ever obey her commands again. However, with Ash's help, she learned how to control her Ledyba with vocal commands. By telling them to "descend at 80 degrees", among other instructions, Arielle's Pokémon were able to defeat Team Rocket. Although the whistle was recovered when Team Rocket was sent blasting off, Arielle continued to train her Pokémon verbally. Brock noted that there was no difference between Arielle's whistles or voice instruction, so Arielle decided to use the whistle less often.

(Source: Bulbapedia)