1. The battle mechanics are completely whack. It's a refreshing take on how to battle but imho just not a very good one. Especially against mons that are around your own mons level feel really bad and more often than not you just lose because the AI doesn't have to switch between buttons and has much more freedom to switch moves.
2. I'm gonna use an example here of when I was just training my Salamon in the sewers to get my point across. I'd be fighting Numemons in there and even the ones 5-6 levels down on my Salamon would easily 2 or 3 shot it anyways. This kind of mechanic was very apparent over every area where overleveling or type advantages wouldn't matter anything. This ties off of point 1 as well.
3. Taking care of your Digimon is just too much, it wants to eat every 10s if you let it. In the end it's basically almost never completely satisfied, it wants to play, it wants food, then it's just laying on the ground grumpy af for no apparent reason. Just doesn't feel like a well implemented mechanic.
4. The training mini game is complete and utter bullshit. So the arrow itself already moves in strides right, so it goes from one place straight to another with nothing ion between. As I was playing on PC I suspected there was something wrong as I also play Osu on a 6 stars and it felt off that it didn't land on the green most of the time i was sure I clicked right. I took it upon myself to investigate further and used CheatEngine to slow doesn the game to 10 and then even 5% speed. What I found is that even if you spam the hell out of spacebar and your click at the same time the game will rarely let you stop in the green to begin with let alone that the arrow even touches the green in a lot of cases. What I mean by this is that with the arrowing moving like it does it will just straight up skip the green zone altogether when it's the 3rd, 2nd and smallest green zones. Even if someone were to get good at the mini game it still feels shitty because it literally won't let you get max points.
5. It would be very handy if at the end of a battle the items you picked up had at least a tag of what category they are if not just straight up which item and what they do. I found myself looking around for what items were even supposed to do let alone even getting to where they're supposed to be at all.
Conclusion: This game has the potential to be great if it is presented less like a grindfest and gets polished around the edges. Type advantages should feel way more fair and the battle system just needs a complete rework, especially for pc it could at least do with bindings to the keyboard so it feels better to battle to begin with.