They briefly appeared in Spidey's imagination of him being in their universe.
Then again, they briefly appeared seeing Living Laser appearing in their Helicarrier and witnessed their Thor knocked the latter out with his hammer, Mjolnir.
Iron Man is the leader of the Super Hero Squad. He wears the Mark IX Armor, but he has holes for the eyes and mouth. When Living Laser transported in the Helicarrier of the Super Hero Squad, he ordered Thor to knock him out.
Wolverine was born a mutant in the Super Hero Squad universe. He has adamantium-enchanced claws and animal senses. When Spider-Man thought about the realities, Wolverine was in his imagination.
Hulk is a green large gamma radiated human, with an oblivious face. He has superhuman strength, from his enchanced radiation strength. When Spider-Man though about the realities, Hulk was in his imagination.
Captain America is a Super Soldier from the WWII era. He has a shield as equipment, with an American design. When Spider-Man though about the realities, Captain America was in his imagination.
Scarlet Witch is born a mutant in the Super Hero Squad universe. She wears a costume covered in red, with a red cape, headband and boots. When Living Laser trasported in the Helicarrier of the Super Hero Squad, she witnessed Living Laser getting knocked out by Thor.
Ms. Marvel is a female super hero, she was mutated by the kree and received enchanced powers. She was a black suit, with a short black mask and a red sash on her waist. When Living Laser transported to the Helicarrier, Ms. Marvel witnessed Living Laser getting knocked out by Thor.
Thor is an Asgardian from the dimension of Asgard. Thor wears a small helmet with tiny bird wings on top, steel armor, red cape and wields the Mjolnir. He speaks an ancient language of English. When Living Laser transported to the Helicarrier, Thor knocked him out. He is voiced by Dave Boat.