The crossover will take place in The Unbeatable Squirrel Girl #6, from writer Ryan North and artist Erica Henderson, and Howard the Duck #6, from writer Chip Zdarsky and artist Joe Quinones.
Here's the story synopsis released by Marvel:
This summer, the two most powerful characters in the Marvel Universe clash! You asked for it... you demanded it... and now you'll get it: GALACTUS versus WOLVERINE! Just kidding, the story's actually about Squirrel Girl and Howard the Duck, and instead of fighting they solve problems together. Sorry for making you think Galactus and Wolverine would fight, maybe that should be our next team-up though since it's not a bad idea at all. Wolverine could get some Power Cosmic on her claws to create the Power Clawsmic and Galactus could be all "OH NO YOU DIDN'T". Anyway, in our story Howard and Squirrel Girl fight some dudes and learn some important lessons and Galactus doesn't even show up once, the end
Hi this is Chip, Ryan wrote all of the above. I have no idea what he's talking about, I just found out about this crossover.
Look for the Squirrel Girl/Howard the Duck crossover this spring.