The Ninja Poke-Showdown - S1-E32
Factual error: When Venonat uses Stun Spore, Ash tells Bulbasaur to use Whirlwind. Bulbasaur just blows the powder away with his mouth, but he doesn't use the Whirlwind attack. He can't learn Whirlwind in any of the games, and what Whirlwind is supposed to do is to blow the opposing Pokemon away. Ash could have just as easily told Bulbasaur to blow it away, but he instead chose to tell him to use a move that he can't possibly learn. The only Pokemon that can learn Whirlwind are either Flying types or Bug types; i.e., Pokemon with wings (with the exception of Makuhita and Hariyama, which weren't introduced until generation III, and did not exist at the time this episode aired). In The School of Hard Knocks (Season 1, Episode 9), a character mentions information regarding a Pokemon's levels, attacks, and information which is taken straight out of the game, so it's very clear that Bulbasaur should not be able to use Whirlwind. [This is a result of mistranslation. In the original, Japanese version Ash orders Bulbasaur to "blow it away." He didn't say Whirlwind. Still a mistake in the English version.]
The Ninja Poke-Showdown - S1-E32
Continuity mistake: When Misty asks, "Brock, what kind of crazy place is this?" her bag is under and next to her, but in the next shot, it's not under her and is 0.33 metres away from her. (00:03:24)
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 Ninja Poke-Showdown - S1-E32
Continuity mistake: When Pikachu tries to remove the webbing on himself, part of Charmander's yellow underbelly turns orange, like the rest of his body. (00:15:35)
The Ninja Poke-Showdown - S1-E32
Other mistake: When the floor in the slanted room tilts, Ash and his friends tilt, but the trapdoor does not. (00:15:19)
The Ninja Poke-Showdown - S1-E32
Continuity mistake: When Ash asks Aya to remove him from the wall, Misty's blue eyes turn white. (00:07:19)
The Ninja Poke-Showdown - S1-E32
Continuity mistake: After Aya slaps Brock, Misty's bag disappears. (00:06:52)
The Ninja Poke-Showdown - S1-E32
Continuity mistake: When Ash and his friends notice a Venonat, Ash's bag disappears. (00:03:34)
The Ninja Poke-Showdown - S1-E32
Continuity mistake: When Brock opens the door to the mansion, he is to the right of Ash, while Misty is to the left. But in the next shot, they swap places. (00:03:02)
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.