Well Kenshin, Trip's Servine proved to be strong - it did defeat Ash's Pikachu when it was still a Snivy. His Gurdurr put up a good fight against Cilan's Dwebble in the Club Battle Tournament and Vanillite tied against Ash's Tepig in a 3-on-3 battle. Tranquill defeated both Ash's Oshawott and Tepig with Aerial Ace while Frillish managed to defeat Ash's Snivy by taking advantage of Cursed Body. Trip also has a Lampent but it hasn't been seen since the episode where Ash's Pidove evolved into Tranquill.
Paul has really strong Pokemon as I said earlier - Honchkrow, Torterra, Drapion, Electivire, Ursaring, Magmortar, Gastrodon, Ninjask, Weavile, Aggron and Froslass among them. Paul has actually used Pokemon of every type except Dragon and Psychic.
Barry's Empoleon is tough with its Hydro Cannon. And don't forget Barry's Roserade (only appeared once) where it defeated Ash's Chimchar despite having a type disadvantage. Barry also has a Staraptor and Heracross (Barry's Staraptor hasn't been seen since its debut) along with a Skarmory and Hitmonlee he used at the Sinnoh League. Barry's team is very similar to his in-game team (assuming the player starts with Chimchar), having Empoleon, Staraptor, Roserade and Heracross, although his in-game team also has Floatzel and Snorlax.
Trip's anime team has some similarity with Cheren in the games (Cheren only has a Servine if the player starts with Oshawott). In-game Cheren has a starter (Serperior/Emboar/Samurott) strong against the player, an elemental monkey (Simisage/Simisear/Simipour) of the same type as the player's starter, as well as Unfezant, Liepard, Gigalith and Haxorus. (Trip and Cheren also share a Tranquill)
Bianca doesn't really look tough but her Pignite hits hard with Heat Crash. Also, her masculine Minccino knows Hyper Voice and it's said that her Shelmet will evolve soon. Also in the games, Bianca only has a Pignite if the player starts with Oshawott. In-game Bianca has her starter (Serperior/Emboar/Samurott) weak to the player's choice, an elemental monkey (Simisage/Simisear/Simipour) strong against the player's starter, as well as a Musharna, Stoutland, Mienshao and Chandelure.
Stephan's Sawk put up a good fight against Iris' Emolga, using Close Combat to block Attract. Even his Zebstrika defeated Bianca's Minccino easily in the Club Battle.
Yeah, I've noticed some similarities there.