If you consider him at all, you can consider Acid Storm one of two ways. First, there’s “Poor Acid Storm”, the lone Rainmaker made into a toy. The chances of his other two brothers ever being made is pretty much nil. However, looking at his robot mode, he does have both blue and yellow, perhaps an homage to the other two? Something I hadn’t considered before is that maybe he’s not meant to just represent one of the three, but all three in one toy.
There’s also “How in the world did a one episode nobody ever warrant his own toy? Awesome!” I am definitely of the second mindset. The Rainmakers were three anonymous Seekers with wildly bright single-tone colour schemes and the ability to generate acid rainstorms. They appeared in the single episode Divide and Conquer under the command of Shockwave back on Cybertron. That Acid Storm even exists in toy form is pretty much a miracle, so I leave it right there.
I was asked about my display peculiarities, so here you go: thanks to the old catalog images and instructions sheets that showed their guns pointed up when not in use blasting Autobots, I tend to keep the original three Seekers’ guns in the up position. For whatever reason, as a kid I never pointed them up on my one Conehead, Dirge, so I keep the Coneheads’ facing down. Acid Storm doesn’t fit into any pre-existing toy rules at all, so just for the sake of variety, I leave his attached to his wings and facing up.
Here we have it, the reason the Decepticons managed to maintain air superiority.