Took a while but a patch (v. 1.1.0) and all the DLC packs are now on the (North American at least) Wii u eShop.

Since I doubt anyone on the staff cares enough to post a news article, I thought I should let the few duders who might know.

From: http://www.nintendoworldreport.com/news/34828

The full list of what is available is as follows:

Free Skins

• Classic Ares
• Containment Suit Doomsday
• Luchador Bane
• Flashpoint Batman

Characters - $4.99 each

• Lobo
• Scorpion
• Batgirl
• Zod

Modes - $2.99

• Zombie Mode (Turn every character in the game into the undead)

Single Skins - $0.99

• Man of Steel Superman
• Blackest Night Batman (Also available in Blackest Night #2 Pack)

Skin Packs - $2.99 each

• Bad Girls (Catwoman, Wonder Woman, Harley Quinn)
• Teen Titans (Raven, Cyborg, Deathstroke)
• Killing Joke (Joker, Joker, Joker)
• Red Son #1 (Superman, Grundy, Wonder Woman)
• Red Son #2 (Batman, Green Lantern, Deathstroke)
• Blackest Night #1 (Superman, Flash, Doomsday)
• Blackest Night #2 (Batman, Hawkgirl, Aquaman)
• Arkham City (Batman, Catwoman, Joker)
• New 52 (Superman, Batman, Wonder Woman)
• Earth-2 (Flash, Hawkgirl, Grundy)
• Ame-Comi (Catwoman, Wonder Woman, Harley Quinn)
• Lockdown (Prison Superman, Knightfall Bane and Batman Beyond)
• Flashpoint - $3.99 (Aquaman, Deathstroke, Wonder Woman)

Wait, wait wait... Why doesn't the Ame-Comi costume appear in the PSN store? Is it Wii U exclusive?

Was the Ame-Comi pack available through any means like the iOS app? Because the Wii U version doesn't link to that and couldn't get the bonuses that way.

Need to install the update so my Wii U will stop yelling at me about it.

Also I think the Ame-Comi pack is Japan exclusive.

Should note that Lobbies are still not in the game for Wii U sadly from what I've heard.