I really like this. BUT...
There are a couple of key issues I have with this game... The first and greatest is that there aren't really any proper instructions for this game, no 'how to play' section that ADEQUATELY explains everything I need to know to play this game. Dx (Unfortunately, your instructions in the author comments didn't really do it for me, as I still found myself wondering what some things did, how to fix other things, and whatnot.) For instance, I don't know what the Jar with 'D-Cu' on it is supposed to do, I wasn't really sure when to give my Digimon the pill, and I downright just have no idea what the bottom-middle button (the one with the monster and 8) was supposed to do. Bottom-line, It needs better instructions is all... I realize it's based on the original D-pet, which didn't explain much either, but you can do better than that! The other issue I had was how quickly and yet slowly time moves... You have to constantly babysit the Digimon so that they don't get sick or too tired or anything, but it feels like it takes forever to progress through the evolutions. I think you could fix that by either remedying one of those problems or the other; make the game at a slower pace like the original D-pet (which admittedly might be difficult), or make it so that it's easier to digivolve faster.
On the other hand, the whole setup looks really cool, and I totally get the feeling of the style of Digimon from it... the hand-drawn characters are also pretty cool, considering you could have just stuck in Digimon pictures or sprites, but opted to make them from scratch instead... so I appreciate that. Although, I think it would have been neat if they had multiple poses and frames, instead of just the same picture that waggles around. I could tell that this is based off of the very first V-pet, and it was really cool to see Seadramon and Betamon show up. :D Although, I was curious as to whether guys like Tyrannomon or Airdramon were included in this one? (I've only ever gotten Greymon and Seadramon.) I've also had difficulty getting past Champion level, it seems like the care demands of the Champs are too great for the Virus meter (I think that's what that is?) NOT to get filled all the way.
Bottom line, it's a pretty cool game... there's definitely room for expansion and improvement, which I would love to see, but for what it is (a recreation of the virtual pets), it's pretty neat. (NOTE: Take it as a compliment that I thought it worth my time to write so much. xD Hopefully you can get past the tl;dr wall of text, hahahaha....)