Revealing mistake: In the English dub, towards the end of the intro, May is slightly transparent and Max's left arm can be seen through her. (00:01:54)
Continuity mistake: In her initial appearance, May is a little taller than Ash. In subsequent episodes, May is slightly shorter than him.
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)
A New Land! A New Adventure!! - S6-E1
Continuity mistake: When Professor Birch gets Treecko's Poké Ball, another one is upside-down, but in the next shot, it is upright. (00:16:59)
Continuity mistake: When Mays, "There might be more to Pokémon than I thought," she is there, but in the next shot, she disappears. (00:11:48)
Continuity mistake: When Ash is talking about the artifact Professor Alden is holding, the button on his jacket intermittently goes from being present to being absent and then back to present. (00:12:00)
There's No Place Like Hoenn - S6-E3
Continuity mistake: In the shot before Ash says that he is hurrying to get to his match, the landscape changes between shots. (00:00:23)
There's No Place Like Hoenn - S6-E3
Continuity mistake: When Ash says, "Oh, sure," the top left part of the wall behind him goes from being red slats to being a cream wall. Also, the right part of the wall goes from having no slats after Ash's bag to having some. Additionally, Ash's marks go from being absent to being present. (00:06:08)
There's No Place Like Hoenn - S6-E3
Continuity mistake: When May looks at her bicycle when it is charred in her flashback, the emblem on her hat to the right of the knot on her bandanna is red with a white lining, but in the next shot, that part is white with a red lining. (00:06:41)
Continuity mistake: When May asks when she and her friends will be stopping for lunch, Ash's bag disappears. (00:00:14)
Continuity mistake: When Max says, "But I haven't even seen one Pokémon yet!" there is dirt, but in the next shot, it disappears. (00:00:21)
In the Knicker of Time! - S6-E5
Continuity mistake: When Ash says, "I should be thanking you," Brock is absent, but in the next shot, he appears. (00:00:46)
In the Knicker of Time! - S6-E5
Continuity mistake: When Nicholai notices that May and Max are wearing shorts, Max's brown shorts turn blue like Nicholai's. (00:04:13)
In the Knicker of Time! - S6-E5
Continuity mistake: After Nicholai introduces himself, the bottom of Max's shirt changes from green to yellow. (00:04:43)
Revealing mistake: When Ash is first seen, his hands clip through him. (00:00:02)
Revealing mistake: When Ash says, "Seems almost magical," the end of Pikachu's tail is missing. (00:03:59)
Continuity mistake: When May says, "It looks like Treecko might be feelin' a little weird around all our other Pokémon," there is a tree nearby, but in the next shot, there is not. (00:00:40)
Revealing mistake: As Seviper slips back into the bush after Torchic trips on its tail, the end of its tail is cut off. (00:03:16)
Revealing mistake: When Ash and his friends run into the Pokémon Center, a line is briefly layered over them. (00:07:06)
Taming of the Shroomish - S6-E9
Continuity mistake: When May is first seen, Max and Pikachu are absent, but in the next shot, they are present. (00:00:06)
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.