1. Online play restricted to a plaza.
Festival Plaza was a travesty that should have been scrapped, yet it is still required to go online one year after S/M.
That heavily discourages the player from trading rare Pok?mon on Wonder Trade, as well as competitive or casual online battling.
2. Unskippable cutscenes
To say that Gen VII went too far is a massive understatement to explain how much of an unplayable mess it is. No replay value really hurts the games.
While I like Lillie, she really shouldn't be hogging up all that spotlight, since it robs objectively better characters like Guzma, Wicke, and even Lana of any potential development.
3. A new recolour form
I really don't like Dusk Lycanroc, since it isn't much of an improvement over the other Lycanrocs. It's just Midday with Midnight's mane tacked on, while painted like a rotten carrot to shill the anime. The concept art even shows just how lazy the effort was.
New forms should shake things up for an existing Pok?mon's design. When the Kami Trio were introduced, they got flak for being recolours, but when B2/W2 was introduced, they got unique-looking forms that helped improve their viability, except for Thundurus, but at least he looks cool as a Therian.
4. Awkward stat distribution (Particularly bad speed)
Gen VII has to be the worst offender of power creep, since too many new Pok?mon lack the Speed or bulk to be usable in VGC. No player should be forced to use older mons and god-like deities that they don't like, yet are the only ones viable for a merciless tournament, because their new favourites have such a atrocious speed stat.
5. Kanto pandering
It's nice to have throwbacks to the classic that started it all, but there's no need to make new mechanics exclusively for some of the original 151, like Regional Variants.
I'll wait and see if LGPE has enough content after the Champion before I make the switch to a hybrid console, no pun intended.