Pikachu: Defeated a Regional Champion's ace (Wallace) -> Fairly Easily
Lucario: Defeated a Master Class Trainer (Regional Champion Equivalent or Beyond) Ace G-Maxed in its base form
Gengar: Basically took down 2 pokemon owned by a (Regional Champion Equivalent or Beyond)
Sirfetch'd: Took out an Elite four member's ace
Dracovish: Took out a Regional Champion's Pokemon who later made it to the master class
Dragonite: Took out the ace of a Regional Champion who later made it to the master class
It feels undeserved cause we barely saw any of these Pokémon training and getting stronger except for Lucario, and even him had a pretty lackluster arc compared to Ash's previous aces. All of Ash's Pokémon are super strong and have stronger feats than pretty much any of his previous mons, which feels undeserving considering all of his previous teams had much more training than the current one.
Dracovish defeated the pseudo legendary of a regional champion in his first battle, and then defeated Drasna's ace. All of this was done with barely any training.
Gengar, Sirfetch'd and Dragonite all follow a similar pattern to Dracovish, though in a less egregious manner. They got strong way too fast if compared to Ash's previous mons. Gengar had 7 battles, Dragonite had 5 and Sirfetch'd had 5, as well. Just for comparison sake, both Dragonite and Sirfetch'd were in less battles than Palpitoad, Boldore, Gible, Glalie, Scraggy, Naganadel, Melmetal and Kingler.