>>45131913To elaborate on what
>>45131957 mentioned, Ash and Giovanni have a brief battle in the Operation Tempest arc of BW, but Giovanni wins, leading to Ash and Pikachu being held hostage.
The early team leaders really got fucked over in the anime. Archie, Maxie, Cyrus and Ghetsis are not even shown owning any Pokémon in the anime. Archie and Maxie didn't even appear at all until the 2-part finale of the Aqua/Magma arc, meaning they got a grand total of 2 episodes of screentime. Cyrus got off the best of the four by getting a decent amount of screentime and a fake persona as a good guy in the anime, and in general Team Galactic was handled better, but there was still room for improvement. The Team Plasma arc in the anime was complete dogshit (thanks in part to Team Plasma's original planned debut getting cancelled).
Lysandre was a dramatic improvement due to the anime giving him a decent amount of screentime in the Mega Evolution specials, focusing on some of his backstory from the games (albeit the anime removed Lysandre's relationship with Sycamore, and turned Team Flare overall from a cult into a generic villain team) an actual party and making him proactive, and taking on elements of BW's game plot in making the climax of the Team Flare arc. And of course, Lusamine got off pretty well in SM considering how different that series was from the games/past seasons, and Guzma was just okay. In general, the villain bosses' portrayals in the anime have trended upwards over time.