Verti-Cal and Horizont-Al were once peaceful gents before devolving into warmongering geometric demigods from the result of their zone being destroyed. Blaming each other, they battled and were arrested by the Zone Cops. They're pretty nice when they're wearing their collars.

The aforementioned collars are known as control collars. When applied, they forcefully restrain the power of the wielder. It may hurt in the moment due to the sudden drop in power, but the wearer will eventually become "comfortable".

Shadow has two lines in the entirety of Worlds Unite, this is because Team Dark is killed off early into the story and then makes an arrogant response to Sonic about his well-being after he called him to make sure he wasn't still dead after reverting the worlds.

Also I thought it was worth noting Sigma gets bodied with hardly any contest in just a couple of pages because they set the final battle on the last issue which normally doesn't sound like a bad idea but then there's a side plot with Eggman and Wily...(1/4)

...where they just might be able to salvage everything and come out on top, but then that gets shafted by Xander Payne, which may or may not have reality warping consequences (pretty minor actually), which in itself takes multiple pages. (2/4)