Trying to find out as much info as I can about the Marvel group The Misfits, which consists of Toad, Frog-Man, and Spider-Kid. Are there any particular paperbacks where stories involving this group appear in? Or was this just a one-time team-up that didn't lead anywhere?
Odds are if you know about the Misfits, you may already know about this, but:
At the same time as he was joining the Misfits, the Toad was also busy being the the Terrible Toad-King in VISION AND THE SCARLET WITCH (1985) # 6, 7, and 11. The Toad had been established as having a rather obsessive crush on the Scarlet Witch (dating back to their times together in Magneto's Brotherhood). Issue 11 guest-stars Spider-Man, and firmly establishes that both the stories are definitely involving the same Toad, and that the Toad is a bit crazier (and far more dangerous) than he seemed in his Spider-Man appearances.
So, when one of your super-team's founding members is an obsessed stalker who's been trying to kill former Avengers in his off-time, it's unlikely that your team is going to be all that successful.
Now, the Vision/Scarlet witch series has been collected, in the trade Avengers: Visions and the Scarlet Witch: A Year in the Life.
The relevant Amazing Spider-Man issues will appear eventually; either in an Amazing Spider-Man Epic Collection, or a Marvel Masterworks. However, it may be years yet before either of those reprint lines hits those issues.
(Just as an aside, I'll note that all three of the Misfits had some connection to the wrong side of the law. As might be guessed from the appearance of his "spider-arms", Spider-Kid was originally a Dr. Octopus fan. And, Frog-Man was the son of the super-criminal ("villain" is too strong a term) Leap-Frog (an old Daredevil enemy), who gained access to his dad's old outfit.)
Seems to be a one-off.
Wikipedia entries for the 3 characters mentioned:
He met and was befriended by Spider-Man, and teamed with Spider-Kid and Frog-Man as the superhero adventurer team, the Misfits. However, Toad suffered from constant depression.
Eventually, Toad left the Misfits and returned to villainy. [Reference to Amazing Spider-Man #266 (July 1985)]
Frog-Man (Eugene Patilio)
He, Spider-Kid and the Toad briefly form a super-team called the Misfits. [Also references Amazing Spider-Man #266 (July 1985)]
Spider-Kid (Steel Spider)
He was involved (along with Frog-Man and the Toad) in a short-lived super-hero team called The Misfits.
Seems to only be in that one issue as mentioned in Marvel Wikia.
The three never appeared together again, so presumably the team broke up soon after it formed.
The Marvel Wikia goes on to mention:
This and the following issue were released because editor Jim Owsley considered having Spider-Man's fight against Firelord from issue #269 take place in a graphic novel or perhaps an annual instead. While debating what to do with the story, he ran these two fill-ins written by Peter David.
As a fill-in, it likely wasn't meant to affect any continuity so no permanent teams or changes. Because it doesn't have lasting effects on story, it does not look like it's ever been incorporated into a Collected Edition of any type.