I have actually been thinking of ways to differentiate the Chain Attack final smash from Robin's fs. I was at a bit of a standstill until I started thinking about Donkey Kong's final smash (stick with me here, I promise you, this is relevant), and how they added a rhythm element to it that boosts the power if you press the A button at the right time. Then I thought about how in Xenoblade chain attacks become stronger if you use arts of the same color in a chain. I tried thinking of a good way to incorporate that into the Chain Attack final smash in a way that would be simple to perform yet still provide some challenge, but nothing came to mind. Then I thought about the little b-button quick time events in Xenoblade that pop up during battle, and thought maybe that would be a good mechanic to incorporate. During Shulk's Chain Attack final smash, the little b button prompt from the game will pop up with each strike, and if you press b once the ring reaches the inside of the circle, the power of the chain attack will be increased (with an added bonus if you hit b just as the ring hits the edge of the circle). Assuming the Chain Attack consists of around 6 or 7 strikes, it would be a good way to separate Shulk's final smash from Robin's, and make it one that rewards players for a skill they acquired while playing Xenoblade itself.