Roars

Roars used in the Godzilla Vengance universe are very different than the originals. They are very diverse, and even the planned monsters had roars of their own.

Godzilla
Godzilla uses mostly recycled 1998 Godzilla roars. His signature roar, which is heard at the end of every episode intro, is a roar used by Heisei Godzilla, but most famously used for Shin Godzilla when he was frozen. In the S1E3 Battle on the Edge, he also uses 1954 Godzilla roars, especially at the end when he lets out an extremely lengthened version of the roar Godzilla makes when he dies in 1954.

In the rejuvenated behind-the-scenes videos, we are shown brief clips of the unfinished episodes. In the rejuvenated clips, Godzilla's roars have changed dramatically. He now uses mainly Heisei roars, and higher-pitched, injured Showa roars. He also uses the louder roar from the anime Godzilla as a victory roar. As burning Godzilla, he uses Millennium Godzilla roars from 2004, along with the elephant-like injured groans.

Kumonga & Kamacuras
Since Kumonga and Kamacarus are supposed to be of the same species, they use the same or often similar roars. They are mainly recycled MUTO roars from G2014.

Mechagodzilla
Mechagodzilla 1 in S1E3 Battle on the Edge does not make any roars, only the occasional "inception noise" foghorn sounds.

Zilla & Zilla Jr.
Both Zilla and his son use recycled Jurassic Park T. Rex roars. His atomic breath is simply a generic Godzilla Atomic Breath sound effect, and his ultimate roar is the more deafening T. Rex roar.

Orga
Orga mostly uses recycled Cloverfield Monster roars from 2008. Its appearance is just as similar.

Kiryu (Mechagodzilla 2)
Kiryu is seen briefly, and he uses his same roars from 2002 and 2003.

Gorosaurus
Gorosaurus uses the same roars used from his first appearance in 1967.

King Kong
King Kong uses the same roars and appearance he used in the 2005 King Kong film.

Mechagodzilla 3
While Mechagodzilla is not seen on screen, he was deployed somewhere in the world, but was destroyed. He was planned to use the original 1974 Showa Mechagodzilla roars.

Spacegodzilla
Spacegodzilla looks much like Shin Godzilla, and consequently uses modified Showa roars, with two breath in moans as opposed to one. This effect was created by overlaying the longer and shorter Showa Godzilla roars.

MOGUERA
MOGUERA is never seen in action on screen. He was planned to not have roars, much like his original appearance in Godzilla VS Spacegodzilla.

Mechagodzilla 4
Mechagodzilla 4 is never seen in action on screen. He looks much like 1993 Super Mechagodzilla, and consequently would have used the same roars.

Gigan
Gigan's roars would have been extremely complex. as non-cyborg Gigan, he was planned to make bird-like chirps that would have been combined with sped-up Megaguirus roars from 2000.

As cyborg Gigan, he would have used the same roars he used in both 1972 and 2004.

As mecha-Gigan, he would have used the shorter Gigan roars from 1972, which would have been combined with Kiryu's roars from 2002 & 2003, to give the final roars a more mechanical effect.

Mothra
Mothra would have used edited versions of her original roars, combined with non-edited versions of them. Since she does not appear in her larval form, the roar used for it is undefined.

Battra
Much like Mothra, Battra is never seen in his larval form, so it is undefined. His Imago form was planned to use his 1992 Larva roars, which the creator said "sounded cooler"

King Ghidorah
For Ghidorah, the creator planned on using Ghidorah's roars from the GMK movie in 2001. He favored these roars over most of the other Ghidorah roars, and it was the first time these roars had been used since 2001.

Xilien Kaiju
Several Xilien Kaiju appear in the Planet X Invasion episode arc in season 2. They include Trespasser, Knifehead, and Leatherback. They all use their original roars from their original appearances.

Xodzilla
Xodzilla used roars akin to the original Spacegodzilla.

Xothra
Xothra used the original Battra Imago roars.

Xattra
Xattra used growling and snarling sounds akin to Godzilla Earth.

Xorosaurus
Xorosaurus used recycled Indominus Rex roars.