Clothing Damage: Of a sort. When an Inkling is "splattered" by the other team, they collapse into ink and their clothes are seemingly blown off (though they spawn with a fresh set back at the starting point).
Color-Coded Armies: Each team of Inklings can have have different colors, which are chosen before a match begins. The color picked for one team also affects the other team's color by way of Color Contrast. So a pink team will always have teal enemies, and vice versa, with purple and blue being the only team color used more than once, purple against green and yellow and blue against orange and yellow.
Covered in Gunge: The whole point of the game is to cover everything in ink, both scenery and enemies.
Curtains Match the Window: The Inklings have irises that match their hair, but only while humanoid — they instead have black irises when in squid form.
Development Gag: The demo stage has a poster of a Blooper in a far off corner. Originally, the game was going to be a spinoff of the Mario series, but Nintendo had faith in the game to make it a stand-alone series.
Domino Mask: The Inklings have black outlines around their eyes, giving them the appearance of wearing masks.
Empty Piles of Clothing: Hitting opponents with weapons will make them disappear while leaving their various accessories like headphones behind.
Expy: The Inklings in squid form are technicolored Bloopers with a longer pair of arms.
Family-Friendly Firearms: Ink guns, ink bazookas, ink grenades, oversized paint rollers... you might see a pattern here.
Field Power Effect: Inklings can swim at high speed through their own color of ink, but can barely move when on the other team's ink.
Girlish Pigtails: The female Inklings have their tentacles take this form in their human forms.
Graffiti Town: The setting of the game is industrial with some suburban elements, while nontheless still being colorful even before the Inklings wreak havoc all over.
Kill Sat: In one of the trailers, it seems there's a way to get an ink version of an orbital strike, what with a huge stream pouring down from the sky into the arena and creating a veritable explosion of paint.
Lighter and Softer: To the usual shooter affair. The game has a very cutesy art style, with guns that fire ink instead of real weaponry.
Mana Meter: There is a meter in the top-right corner of the screen that, when filled completely, gives a super weapon. The one in the demo was a bazooka that creates a twister of ink, but several others were shown off in the trailer, including a giant paint roller and the aforementioned Kill Sat.
Real Is Brown: Defied gloriously, despite the game's industrial setting. Not only is the game deliberately cartoonish, but it's also one of the most vibrant and colorful games on the Wii U. * And yes, we're talking about the fact that the characters fire a vibrant range of ink in any direction.
Shout-Out: The Inklings look vaguely like Bloopers, especially with the dark marks around their eyes, and the demo stage actually features a poster of a Blooper in an out-of-the-way corner.
Sprint Shoes: Inklings can quickly swim along ink of their color and resurface elsewhere. Particularly convenient for bypassing fences or sneaking up on nearby enemies.
Stealth-Based Mission: The development team has said that one-on-one matches will have "a lot more stalking and hiding in the ink" compared to other modes.
Voluntary Shape Shifting: The playable characters turning into squids. Well, squids that turn into humanoids. Squids made of ink. It's a bit weird.
Wall Crawl: Spreading ink up along a wall allows you to swim up it to cover more ground more quickly.
Warp Whistle: Of a sort; turning into a squid allows the player to super jump to one of their teammates. This can mean warping to the back of the enemy's base for easy inking... or jumping into the wrong end of a firefight.
Widget Series: Squids turn into kids with paintguns to shoot paint for the squids to swim through in an industrial setting, and also the referee is a cat.
You Gotta Have Blue Hair: OK, so maybe it's not "hair", strictly speaking, but the Inklings' heads are the same bright colors as the ink they're spraying.