A New Land! A New Adventure!! - S6-E1
Revealing mistake: In the English dub, during the "Who's That Pokémon?" segment, part of Lanturn's tailfin is cut off. (00:11:39)
Fierce Battle in the Monster Ball Factory! Pikachu VS Nyarth!! - S18-E34
Revealing mistake: After Pikachu points to Ash's friends, Ash's left hand passes through him. (00:17:39)
Fierce Battle in the Monster Ball Factory! Pikachu VS Nyarth!! - S18-E34
Revealing mistake: When Ash and his friends put all their Poké Balls in the case, Bonnie's hands are briefly drawn like Clemont's. (00:03:04)
The School of Hard Knocks - S1-E9
Revealing mistake: In the English dub, when showing the front of the flyer, it has filler text that is not related to what it is about. Also, its Poké Balls are slightly transparent and its picture can be seen through it. (00:05:43)
Haruka Travels Through Time!! - S9-E12
Revealing mistake: When Edna gets her parasol, it teleports to her. (00:05:34)
Charmander: The Stray Pokemon - S1-E11
Revealing mistake: When Brock passes Misty when he leaves the table she is at, he clips through her and the stool she is sitting on, and after he does, part of the former is missing. (00:07:08)
Which Wurmple's Which? - S6-E21
Revealing mistake: When turning to agree with Brock, May and Max duplicate. (00:07:19)
Revealing mistake: After Ash says that it is his and his friends' duty to show that it is wrong to use Pokémon for wrongful deeds, part of Pikachu is missing. (00:07:34)
On a Wingull and a Prayer - S6-E18
Revealing mistake: At the beginning of the episode, when Pikachu speaks, his mouth duplicates. (00:00:05)
All Things Bright and Beautifly! - S6-E13
Revealing mistake: When Ash opens a door, Pikachu's tail clips through the doorway and wall. (00:11:26)
Pokemon, I Choose You! - S1-E1
Revealing mistake: When the second crowd is cheering, a woman's dress is not fully coloured in. (00:07:35)
Mystery at the Lighthouse - S1-E13
Revealing mistake: When the costume's right arm falls off, the shell is not fully coloured in. (00:12:32)
Mystery at the Lighthouse - S1-E13
Revealing mistake: As Krabby's Poké Ball begins wobbling, the light on it briefly shifts to the left. (00:04:36)
Mystery at the Lighthouse - S1-E13
Revealing mistake: When the costume's left arm falls off, the shell is not fully colored in. (00:12:33)
Revealing mistake: When Ash goes to save the Pikachu in the river, he clips through his and Misty's bags. (00:05:25)
The Water Flowers of Cerulean City - S1-E7
Revealing mistake: In the localizations, when Ash and Brock begin running to the crime scene, part of the top of Ash is missing. (00:04:25)
Revealing mistake: As Ash, Misty, and Tracey are making their way through the crowd, Tracey clips through one of the people in it. (00:05:33)
The Ninja Poke-Showdown - S1-E32
Revealing mistake: When Pikachu turns his head after a Venonat leaves, his left ear clips through Ash. Also, part of Ash's right leg is missing. (00:03:46)
The Path to the Pokemon League - S1-E8
Revealing mistake: When A.J. and his Sandshrew walk into a tent, A.J. and his whip clip through the tent. (00:07:56)
Don't Touch That 'dile - S3-E1
Revealing mistake: When Officer Jenny takes Totodile from Ash's hands, her right hand clips through it and Ash's left hand. (00:17:50)
Answer: He is a good guy but just found himself in a bad situation when he worked for Lysander. He didn't want him to harm Ash and his Pokémon when he was trying to get the special bond between Ash and his Greninja to work. He does leave Lysander and go back to being a good person.