This lengthening of a succulent is a process known as Etiolation. It’s not getting enough light, so it’s stretching out as much as it can to try and get more light to each petal. The color change is also likely from the lack of sunlight as well. I’d suggest moving it to a window where it gets more light.

Either too much or not enough sunlight causes some succulents to turn purple, and judging by the growth pattern and lighter colour of the leaves, it seems like it doesn't get enough sunlight. It being so focused in those areas where leaves are attached would probably indicate it's trying to heal up some wounds, and trying to protect it from sunlight.

As to why it's dropping seemingly healthy leaves, I have a theory. If I see this correctly, the roots are popping out everywhere, indicating that it has nowhere to go. This will slow down growth and it will drop older leaves in order to sustain the growth.

That's just a theory though. Personally, I would repot it into a bigger (plastic) pot with drainage, and place it somewhere that gets a bit more sunlight and track how it's growing.

Would also appreciate a higher res picture to definitely say it's the roots and maybe check out the specks on the leaves, as that could be a disease.

The leaves look like they're shriveling. I also see some aerial roots. That could either be a sign of not enough water, or too much, leading to the roots dying and the plant dropping leaves out of stress. I would gradually expose it to more light as well as it looks etiolated. So I would put it in a full sized real pot with good drainage so that it has a nice, regular amount of water delivery, and the greater light will ensure it can use that water adequately (and not get root rot)

Man, that really succs.

Clearly it's the wrong type for Bulbasaur