The Other Darrin: Continuing the trend started by Star Fox Adventures, the English dub had literally nobody from past games reprising their roles. The Japanese version also has this, though to a lesser extent, with Fox being voiced by Kenji Nojima instead of Shinobu Satouchi and Wolf being voiced by Mahito Oba instead of Hisao Egawa.
Both Leon Powalski and Panther Caroso are voiced by David Scully (aka Dimitri from the Sly Cooper series). In the Japanese version, seiyuu Yusuke Yumata voices both Andrew and ROB 64, while Hirohiko Kakegawa does Beltino, Tricky, and James.
As mentioned above, averted with Wolf and Fox; Shinobu Satouchi voiced Fox and Leon in 64; Satouchi now only has Leon, while Kenji Nojima now voices Fox. Similarly, Hisao Egawa did both Falco and Wolf; now Mahito Oba voices Wolf.
Krystal and the aparoid queen's (real) voice are voiced by Alesia Glidewell (aka Carmelita from Sly 2: Band of Thieves).