They probably hated Torkoal which explains why they gave it that annoying crying trait and had him lose his only BF battle.
And I think they hated Glalie too and only had Ash's Snorunt evolve so that Ash would have another strong Pokemon for the Hoenn league.
tbh, i don't think they hate Glalie as a line though. It has appeared in every series since its introduction (Except for XY, but that was made up with it appearing in the Volcanion movie, which is a gen 6 one). It has even appeared twice in SUMO and Journeys.
Heck, i am even gonna make the bold statement someone at the Pokemon Company/Gamefreak has Glalie as its favorite mon, due to it appearing in every game/generation since its debut (Even getting a Mega in ORAS, despite Glalie being one of the least obvious mons to get one), except for gen 5 and obviously Lets Go and is obviously gonna appear again in the Sinnoh remakes and most likely also Legends Arceus.
With certain Pokemon, it might look they are hated due to the treatment of Ash's, but look at Boldore for example. It only skipped XY as a series. However, since then, it has appeared 10 times in Sun and Moon and 3 times in Journeys. But this are only the major and minor appearances, it has appeared far more as a background mon in other Journeys episode (It even appeared as a wild Boldore in the falinks episode as a background mon).
However, the biggest disliked normal (So non-legendary) Pokemon is Klang. It has yet to appear in the Pokemon Anime and we are three series in after its debut.