Tom Tataranowicz admitted he had not really cared much for the "robin's egg blue" costumes of the 1st Season. He felt that they lacked a certain "cool factor quotient" which he felt that Super Heroes should posses. He didn't want to get too retro when revamping the costumes so pretty quickly he zeroed in on the dark blue costumes that John Byrne had drawn for the FF in during the 1980's.
The vast majority of episodes in Season 1 consisted of fairly accurate re-tellings and re-interpretations of classic 1960s FF comic book stories by Stan Lee and Jack Kirby. The Season 2 episodes also drew upon John Byrne's 1980s run on the Fantastic Four comic, in addition to further Lee and Kirby adventures.
The reason there is no voice actor for the voice of Blackbolt is because Blackbolt doesn't speak because he can destroy Attilan with but a whisper of his voice. He somehow has a telepathic rapport with Medusa (episode 2.03 "Inhumans Saga Part 2: The Inhumans Among Us")
There was some resistance at first about changing the costumes because of the toys. While it is all too easy for producers to harshly bad mouth toy company influences on shows, they do pay the freight and have needs that should be adequately while also creatively addressed. Toy Biz was more than reasonable with the crew and quickly approved everything with Avi Arad also on board for getting the best quality show possible.
Tom Tataranowicz said in an online interview the crew did not have any idea if there would be a 3rd Season or not, but after seeing how the new season was not being promoted as different and kinda felt like it was just being "dumped" out there, the handwriting seemed to be on the wall. The crew quickly moved on to developing The Incredible Hulk (1996) series.
If the show had been picked up for a 3rd Season, Tom Tataranowicz wanted to go into the whole Sue Storm pregnancy story arc. That also would have given a chance for the the Sub-Mariner to return as he played into the whole thing (ala Fantacic Four issues leading up to and around issue #100). Tataranowicz also considered bringing Medusa and She-Hulk into the mix as part of the team.
Since this was a syndicated show, one of the advantages it had was not having to deal with network interference. While network input is often sensible and even constructive, any producer of any kind of show, be it animated or live action, can tell you that network input can often be puzzling at best.
For the first time outside of the comics, Black Bolt is featured as the leader of the Inhumans. In the previous 70's The Fantastic Four (1978) cartoon, the Inhuman's first animated appearance, Medusa was the leader of the Inhumans.
For revamping the look of the characters themselves, much discussion was initially held about working in the Jack Kirby style. Tom Tataranowicz was not for that. Though Tataranowicz personally liked and admired Kirby's work, he felt that the strength of Kirby's own unique talent carried the look of his designs to such an extent that trying to execute it in animation would require animators to try and capture that and would surely disappoint. That was why Tataranowicz proposed using the John Buscema look to the characters. Not only was it Kirby-esque to some degree, it had the added value of being more realistic - a style which Tataranowicz felt that the PASI animators in the Philippines were comfortable with and could execute nicely. Also John Buscema was hire to do some initial Model Designs of the characters' faces for them to use.
For the Season 2 opening sequence, Tom Tataranowicz wanted to cover the scope of the history of the Fantastic Four by not only showing their origin, by featuring several classic Fantastic Four comic book covers brought to "life." The series composer, William Anderson, did a theme and Tataranowicz drove around for hours in his car listening to it over and over. He admitted that is one way that he likes to work on conceptual things, especially Main Titles, just letting images come to mind that the music inspires. Tataranowicz then wrote up a Beat Script and Dick Sebast did the Storyboard.