I don't play splatoon so I have 0 familiarity with the character designs, but it looks like the arms on the purple one are attached a bit too low. The shoulder is basically missing, if you moved the arm a bit up and turned the top line into one line (instead of the v-shape it is now) it would look ok. On the green one the boobs (is that what they are? That bulgy part of the chest) come up a bit too high and it looks like there just isn't an armpit anywhere.
Nice colors btw!
These drawings are a good start! Others on here are saying you should use a darker pencil but I think you could just as well switch to scanning in your drawings, or at least taking photos in better lighting and adjusting the contrast before uploading.
IMO the 2-minute drawings are the best of the lot, in terms of proportions and getting the gesture down. For longer poses it would help to first quickly map out the shape like you do in the 2-minute drawing, without overthinking it, and afterward going back and adding detail.
It is good that you are looking for landmarks and seem to have started thinking about anatomy. That said, when you draw you might want to pay more attention to what exactly is in front of you-- the angles and proportions in your drawings are a bit all over the place. A good way to improve on this is to use your pencil, you can hold it up to the reference picture to examine the proportions or angles and check them against your drawing. Also, in the particular poses you chose, it can be helpful to sometimes draw the negative space (e.g. the space between the top guy's legs). Overall they are good drawings! Also, thank you for including the models.
