So we're now approaching "The Blackest Night", the final war between the various Lantern Corps of the emotional spectrum. Green, Red, Blue, Black, Orange, Violet, Yellow, and Indigo will all slug it out for the fate of the DC Universe! But obviously, they'll need reinforcements. After all, the more ring-bearers the better. So I'm coming to the aid of the Corps as well as the writers of the mega-event by suggesting some additional characters who could participate in the battle to end all battles, some well-known mainstays who could really stoke the fans' excitement and get them talking.
For the Red Lanterns, the color of "rage", the obvious choice is Animal. Sure, Kermit the Frog has his occasional outbursts of temper, but how can even Atrocitus compare to a barely-contained beast whose fury is such that he only bowls overhand? If anything, Animal could wind up leading the Red Lantern Corps.
And who better to join the Orange Lanterns ("avarice") than Oscar the Grouch? He wouldn't be a leader, but his fervent passion for scavenging the unwanted relics of modern society would give him a power that would endure while other members of that Corps were defeated. Others might covet money, wealth, gold or gems...but how do you stop someone who can even want an old torn sneaker with that same degree of intensity? Oscar could be the Orange Lanterns' secret weapon.
An important thing to keep in mind, when picking someone to join the Yellow Lantern Corps, is that you're looking for someone who inflicts fear, not someone who is fearful themselves. With that in mind, I'd suggest Statler and Waldorf. These two are well-known for being able to reduce full-grown bears to quivering, whimpering bundles of nerves with nothing more than their acid wit. Imagine what they could do to Kyle Rayner? ("I hear he designed that costume himself!" "Sure! Nobody else would admit to it!")
And of course, who knows better than Kermit the Frog that it's not that easy to be a Green Lantern? He's had experience managing large numbers of strange-looking creatures with diverse temperaments and getting them to work together, and he knows sinister secrets about the emotional spectrum that the Guardians might be hiding from others. ("Rainbows are visions, but only illusions, and rainbows have nothing to hide...so we've been told and some choose to believe it, I know they're wrong, wait and see...")
It's almost hard to choose a single member for the Blue Lanterns, the color of hope. After all, there are a lot of very optimistic characters out there to choose from. But I'd have to say that Gonzo the Great best symbolizes the hope that characterizes the Blue Lantern Corps--after all, he sincerely believes that someday, people will watch him eating a rubber tire to the music of "Flight of the Bumblebee" and call it Art. That takes a lot of hope.
This could have the potential to create some serious drama and conflict in the story, because the Indigo Lanterns of compassion have chosen Camilla the Chicken to aid them in this epic conflict. With her constant selfless concern for Gonzo's well-being, her loyalties will be torn to the breaking point. (I'm expecting that this will be the moment that all the fans remember.)
And of course, Star Sapphire's irrational obsession with Hal Jordan is nothing next to Miss Piggy and her love of Kermit. This makes her the perfect choice for the Violet Lantern Corps, who use the power of love to fuel their rings. And unlike that wussy Carol Ferris, Miss Piggy's fully capable of defending herself even without a ring. Hiiii-yaa!
Which just leaves the Black Lanterns, the Corps of death. Several prominent deceased DC characters have already been revealed to be Black Lanterns, such as the Martian Manhunter and the Earth-2 Superman, but their terror pales next to that of Uncle Deadly, the sinister Muppet inspired by none other than Vincent Price himself. The Uncle Deadly/Mogo fight is going to be one that fans are talking about for ages.
In fact, if DC takes my advice, I think fans will be talking about this whole crossover for ages.