To me, the words Pokemon Picross sound like a tiny, adorable puzzle game, a concept that would be an easy win for developers. And the core gameplay is pretty much that, a standard Picross experience where you unlock different Pokemon along the way. Unfortunately, there are so many things here that drag the gameplay down:

The main mechanic everyone will hate is a mobile-game-like bar that lets you fill in only so many sections until the bar has run out and you're prevented from playing the game for an annoyingly long amount of time. When the eShop was still up, you were able to purchase "Picrite" to fill up the bar instantly or unlock new stages among other things.

Every Pokemon you find has an ability that helps you solve puzzles. This sounds like a nice idea in concept, but in reality I never want to use the abilities because I'd just rather solve puzzles without the help.

You can also get Picrite from completing missions and achievements.
The missions are mostly pretty boring objectives without much substance, can't be completed until you've solved the next few stages or force you to use abilities.
The achievements would be an okay addition to the game if it weren't for the fact that you have to claim your rewards by finding the new achievements in a long list that is annoying to navigate.

The only fun addition to the core gameplay are daily challenges where you have to solve multiple puzzles in a row on a timer.

All in all, I can't believe how much they were able to butcher a concept as simple as "Pokemon Picross" and the only remaining positive here is the fact that it's a Picross game.