I'm sure our main's all have a skin line they were included in that didn't exactly make sense, or that you didn't see coming. For me, as a Maokai lover, that would be Goalkeeper. How he's involved in this skin line I'll never really know, but those soccer ball seeds are one of my favorites.
So what line is your main in that you didn't see coming?
Not a J4 main, but Darkstar was so far out of left field it came from right field.
'm sure our main's all have a skin line they were included in that didn't exactly make sense
I'm a Taliyah main. Only skin we've ever gotten is when Crown asked for one after winning worlds. : ^ )
As Nami main, so far 80% water based skins and one Worlds one, none are shocking. Programme is nice but just fits with Soraka's one.
On the subject however, good old Scared Sword Janna.
Riot: "Hey guys, here's a preview image of a skin line which has a floating sword standing on end."
Fans: "Oh cool, a Shen skin."
Riot: "What? No, it's obviously Janna. Also, here's a Yi one 5 months after his last skin."
Any Diana skin :( 
PROJECT: Jhin.
I don't see a reason to include him in PROJECT other that to have him be a villain. He already has a robotic skin in the form of High Noon, which I believe is a reference to his original concept.
I mean, he's scary as hell in the PROJECT universe, but I feel like there were others who may have been better suited for the skin/role.
Odyssey Sona...
The upcoming Praetorian Graves. Seriously disappointing to a Graves main, and completely out of left-field. Jailbreak is still his worst though.
Super Galaxy Kindred. NOBODY saw that coming
Ace of spades Ezreal kinda came out of nowhere
Odyssey Malphite was a bit unexpected.
Trick-Or-Treat Ekko. Really didn't see the skin that finally gives Ekko a baseball bat being.. a trick or treat theme. My hopes for Lil Slugger Ekko are gone.
