One of the realities in Marvel Strike Force is that the gear crunch is real. While each gear Tier requires you to equip 6 items on your heroes and villains, often times hard to find or oft-used pieces are needed to craft these pieces at higher gear Tiers.
Once players get to gear Tier 12 we start to see orange pieces needed to level up to Tier 13. The orange gear pieces can be extremely hard to find making a single gear piece a month-long (or longer) process. While this is good for keeping the game around and players challenged well into the future, it can also be seen as such a grind that players will not bother to continue the effort.
Superior Unique Items are those items needed for specific characters to level their gear up. Like with anything, some items will be easier to acquire than others, but the list below shows us a breakdown of what gear pieces match which specific characters. Special thanks to MSF YouTuber Tauna for putting together this awesome infographic and be sure to check out his YouTube channel.
Above is a more recent version of this Superior Unique Orange Gear Items graphic since it was first created by Tauna as new characters have been added and additional characters have been discovered.