Set Out to the Sea! Line of Chonchie!! - S5-E3
Revealing mistake: When a Chinchou hops up some stairs, it clips through the last step. (00:00:47)
Okutank and Teppouo! Whirlpool Cup Preliminaries!! - S5-E6
Revealing mistake: When Ash gets his Pokédex, it and his right hand appear from thin air. (00:05:56)
Natio's Big Prediction! - S5-E25
Revealing mistake: When Ash takes his Pokédex out, his right hand clips through his right trouser pocket. (00:03:26)
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.