I also like this, but i have to add, that with brushes in ranked, your result is based on how much work you're willing to put in. I've used all three, now four (Yay new octobrush) in ranked. While you are a support weapon; covering ink, making paths, etc, moreso with octobrush, for me, flanks are the most important thing a brush can ever do.
Stealth Squid is important, but treat it like training wheels. To be honest, Stealth Jump shouldn't be used, in my opinion anyway. It's something that helps, but takes up a main ability that could be even more helpful. Besides if you run Vanilla octobrush, you want people to see you super jump, so you'll have someone to target when you land as a kraken. If it's too much then jump back. Same goes for Inkbrush noveau.
As for what modes you can use them for with best results. It's all of them, like i said previously, put in work and the results show. But, brushes generally have a hard time in RM, everyone's attention is not going to he on rainmaker, it's going to be dispersed arounf the field making sure they have ink to get the rainmaker where it needs to go. You are flanking tool, and as such you have to blindside the enemy for you to be effective for your team.
And most importantly, i do recommend trying abilities that either focus on you coming back from being splatted, i.e. special saver, quick respawn or comeback. Or abilities that have more effect as you are alive, Special charge up, dmg up or defense up. I personally run swim speeds to match the brushes orginal roller speed to get in and out quickly.