I have not bought any of the five new Amiibos yet, although I do enjoy the Squid Amiibo - Except, of course, for the limited ink challenges. Sure, the sponge garden was alright, and I even mastered the Invisible Ink (Don't ask how, about 5 deaths/splats were included in part of the learning process) but I actually did have a lot of trouble in Spongy Observatory. There were just these...critical moments...that I seemed to miss, e.g. when there are two sponges and a Twintacle Octotrooper across them, it took a bit to learn that I should actually splat them as opposed to throwing a bomb, which, enevitably, used up about one whole [ink tank].
The roller was harder per se in the majority of the levels, especially the flooded levels because you are basically right behind your roller. On the other hand, with the charger, you can easily make a clear, straight path with little effort and swim through it. Alternatively, you could just use a seeker. :p
The inkling girl with her charger can be extremely convenient in a lot of levels...and extremely inconvenient in others. I'm gonna be honest and say this is my least favorite Amiibo. However, I still do enjoy it very much...especially hitting far-away Octarians when they least expect it! I did have some trouble with the Octolings in Blackbelly Skatepark. It's more accurate to sniping in Turf War/Ranked Battles (Which I am still learning! First thing on my Splatoon Bucket List is: Becoming a good enough sniper! :D
I have beaten all of the challenges except DJ Octavio with the Inkling Girl Amiibo. There have been some pretty hard ones and pretty easy ones. But the point of video games, to me, is to have fun. And that's why I enjoy all of the Amiibos. ~
(Thank you people who actually read this instead of skimming through the text lol)