Ranma Saotome & Akane Tendo (Ranma 1/2)
Shampoo & Mousse (Ranma 1/2)
Ryoga Hibiki & Ukyo Kuonji (Ranma 1/2)
Tatewaki Kuno & Nabiki Tendo (Ranma 1/2)
Dr. Tofu & Kasumi Tendo (Ranma 1/2)
(Many of these Ranma characters can be mix-matched in various ways that could still work, along with throwing in girl-type Ranma)
Sister Rosette Christopher & Chrono (Chrono Crusade)
Andy Bogard & Mai Shiranui (Fatal Fury/King of Fighters)
King & Ryo Sakazaki (Art of Fighting/King of Fighters)
Momiji Fujimiya & Mamoru Kusanagi (Blue Seed)
Jill Valentine & Chris Redfield (Resident Evil)
Tuxedo Mask & Sailor Moon (Sailor Moon)
Goku & ChiChi (Dragon Ball Z)
Heero & Relena (sp?) (Gundam Wing: Endless Waltz)
Floyd Pepper & Janice (Muppets: The Electric Mayhem)
Kermit & Ms. Piggy (Muppets)
Gonzo & Camilla (Muppets)
A bottle of Coke & a bottle of Pepsi
Joker & Harley Quinn (Batman)
Superman & Wonder Woman (DC)
Rock & Revy (Black Lagoon)
Pikachu (Pokemon) & an oven
Big Macintosh & either Rainbow Dash or Princess Luna (My Little Pony: Friendship is Magic)
Princess Cadance & Shining Armor (My Little Pony: Friendship is Magic)
Rarity & either Spike or Trender Hoof (My Little Pony: Friendship is Magic)
Maka & Soul (Soul Eater)
Cloud Strife & Tifa Lockheart (Final Fantasy 7)
Karin Maaka & Kenta Usui (Karin)
Kanako Miyamae & Mariya Shido (Maria-Holic)
Tsukune Aono & Moka Akashiya (Rosario Vampire)
Natsuno Yuuki & Megumi Shimizu (Shiki)
Keiichi Maebara & either Rena Ryugu or Mion Sonozaki (When They Cry)