Superman (Danny Dark) and Robin (Casey Kasem) were the only two characters voiced by the same performer in every "Super Friends" series.
The characters of Plastic Man and Green Arrow made their first animated appearances on this show.
The characters of Wendy, Marvin, and Wonder Dog were introduced to the DC Comics Universe over 30 years later in Geoff John's 'Teen Titans' series around 2006. Marvin would be subsequently killed off (by a rabid Wonder Dog, no less) and Wendy made paraplegic by the writer who took over after Johns left the title two years later.
Adam West who performed as Batman in the live action 1960s television series, lent his voice to animated depictions of the title character in Super Friends (1973) and "Super Friends: Galactic Guardians" (1985)_. He performed that same role in live action form for the television special "Legends of the Superheroes".
When ABC was rebooting its Saturday morning Cartoon serial "Superfriends" (which in 1985 was to be retitled the "Legendary Super Powers Team: Galactic Guardians") they sought out high profile actors to play some of the parts of the superheroes. They reached out to Lynda Carter to voice the character of Wonder Woman at this point. Adam West, who played Batman in the live action TV series; had agreed to play Batman this season; and show producers hoped they could strike gold again by having another iconic actor associated with a DC hero take part in the series. But Lynda Carter said no; she had other commitments. (In interviews she has said she has been approached several times since Wonder Woman was cancelled to do a reboot or a reunion special; like they did several times with Six Million Dollar Man/Bionic Woman reunion movies. Carter said these reunion movies often turn out "pathetic"; so she always turns them down).