Since Disney has ordered a second season of 26 episodes, it is said to focus on the origins of Iron Fist, Luke Cage, and Nova. And it is said that Spider-Man will team up with more heroes too.
Now as for the superheroes we want to see, some of them will be depicted in their marvel cinnematic film incarnations and some of them will be depicted in their Avengers EMH incarnations and here they are
Ghost Rider
Ghostrider is one of the few superheroes that hardly appeared in 21st century animation but because he appeared in the live action films, he maybe appearing sometime in the Ultimate Spider-Man voiced by either Keith Szarabajka or Richard Grieco
Captain America
Captain America may have cameoed in the first episode of season one but he wasn't voiced. Unsure on when he will make his official episode debut, he will serve as an honerary hero and idol to the wall crawler Spider-Man and he is most likely to be reprised by Brian Bloom from Avengers EMH or by his film actor Chris Evans as rumors say
The Wasp
Wasp is a very good superheroine and she appeared in Avengers Earth's Mightiest Heroes as the shows #1 favorite character. She is just like Spider-Man in certain ways by origin, being responsible when fighting crime, flirting around with humor, and are dressed like insects. If she does appear in Ultimate Spider-Man, she and Spider-Man will make a great team at fighting bad guys and flirting around with them as well and since Colleen O'Shaughnessey inspired many MARVEL fans as the voice of the character, she will indeed reprise her role as Janet van Dyne for sure.
Blackwidow
Black Widow appears in the Marvel Cinematic Univere in films Iron Man 2 and The Avengers as one of the 6 superheroes of the Avengers. Sure enough she will very much appear in Ultimate Spider-Man in her Avengers film incarnation voiced either by Tasia Valenza for a certain Russian accent or by Kari Wahlgren so that the character sounds like Scarlett Johanson from the movie.
Hawkeye
Because Hawkeye appeared in The Avengers film as one of the six superheroes to fight Loki and the Chitauri, he is very much likely to appear in the Ultimate Spider-Man series in his movie incarnation voiced by either Josh Keaton or by David Kaye just so that his voice matches Jeremy Renner.
Black Panther
Because White Tiger appears as Spider-Man's one and only superhero girlfriend and teammate, Black Panther may have a chance to appear so that he and Tiger can team up like two black and white cats against their enemies and James C Mathis III from Avengers EMH should have the right to voice the character again.
Vision
Out of all the superheroes that haven't appeared much in the small screen of animation, Vision deserves a chance to appear in Ultimate Spider-Man and one actor suitable enough to voice him is James Horan
War Machine
As Iron Man's #1 sidekick in the arrogant armored hero's universe, War Machine is also Tony's best friend James "Rhodey" Rhodes. He may not have been in the series yet but he will eventually and one guy that's cool enough to voice him is Gary Sturgis
Quake
Daisy Johnson is an agent of S.H.I.E.L.D. and a mutant superheroine called Quake. She is able to cause tremors and earthquakes at a certain mile radius within her vicinity and she will rock Spidey's world if she does appear and either Lacey Chabert reprises her role or Danica McKellar will voce her in the show.
Now as for the supervillains that will be appearing in season 2, very much some of them will be making their first appearance into the marvel animated universe and some of them from Avengers EMH will be sure to appear as well.
Graviton
As one of the many supervillains that were never seen for such a long time, Graviton should appear in the Ultimate Spider-Man series as the main villain for season 2. He would have a connection to Peter Parker's parents and he would bring about the Acts of Vengeance storyline. Ron Perlman will be the one to voice this ultimate villain if he ever does show up.
Blackout
As one of Ghostrider's major enemies, Blackout is one of the many villains that was never seen before in animation. He is one of the most unpredictable supervillains in all Marvel comics and because he is capable of trapping many people in darkness within his vicinity and is super strong, superfast and edgial, he is one tough adversary for Spider-Man and his teammates to take on. If the creators of the Ultimate Spider-Man animated series feel safe on including Blackout for the show in his movie incarnation, Blackout would appear as one of season two's main villains and instead of making the character act solo, he is to have an army of thugs working for him along with other supervillain allies. And if Blackout does appear, either actors Johnny Whitworth (actor that portrayed the villain from Ghostrider: Spirit of Vengeance) or Nolan North would be the best to voice the character himself.
Certain villains that will be working for Blackout are
The U-Foes
The U-Foes are one of the most dangerous group of villains in the Marvel comics. They have only appeared in Avengers EMH and the Incredible Hulk Video game. If they do appear in Ultimate Spider-Man, they would serve as Blackout's best enforcers.
Piranha Jones
Piranha Jones is one of Luke Cages enemies in the Marvel comics. Since Luke Cage is one of Spider-Man's teammates, there is a chance that Piranha Jones will appear as one of the villains that will appear in future episodes. Since he's got steeljaws, he would fit into Blackout's gang of villains for sure. If he does appear, Rick D. Wasserman is the best choice for the voice.
Mangler
The Mangler is one of the villains who was never seen in the cartoons for a long time until Avengers EMH. He would indeed serve as one of Blackout's allies for sure.
Kingpin
Kingpin is one of the most powerful crimebosses in New York City. He would serve as one of the gang leaders participating in the supervillain gang war that is yet to come in the Ultimate Spider-Man series and Frank Welker the voice god of LA is the best guy to do him. Kingpin will also have supervillains working for him too.
Bullseye
Mister Fear
As a Marvel comic version of the Scarecrow, Mister Fear is yet to appear in the series for all our sakes voiced by Lex Lang
Gladiator
Mandarin
As Iron Man's greatest enemy and with Spider-Man having his moments looking over the details of the villains, Mandarin would be an excellent choice and Oded Fehr would fit the character just fine.
Whiplash
As one of Iron Man's enemies, Whiplash would appear in the show in his movie incarnation voiced by Troy Baker
Symbiotes
Carnage
As Venom's offspring, Carnage is badder,deadlier, and more powerful than Venom. If Carnage shows up as Cletus Kasady, Mark Hamill who voiced the Joker should be the best guy to voice the character
Lasher
Lasher would appear voiced by Charles Adler.
Toxin
To find out, stay tuned for future updates.