Name's the Same: There is another, completely unrelated movie Obscurus Lupa reviewed called Monster High (that predates the franchise) which contains gory shots of people exploding and gratuitous amounts of Rape as Comedy. Pray that an unwitting parent hasn't confused the two.
Deuce, starting with the "Why Do Ghouls Fall in Love?" special, is now voiced by newcomer Evan Smith. Smith also replaced Yuri Lowenthal as the voice of Gil. Cam Clarke filled in as Deuce's VA until Evan was cast. The vocal change also marked a change in his personality that not everyone agrees with.
Clawd was initially voiced by Yuri Lowenthal for "Fur Will Fly" for only one line; he's currently voiced by Ogie Banks.
Heath was voiced by Yuri Lowenthal in Season 1, but Cam Clarke voices him in Season 2.
Talking to Himself: In Season 1, Yuri Lowenthal did the voice of every teenage male character. Season 2 brought on more male voice actors to replace Heath Burns and Clawd Wolf, but Yuri still does the voice for both Gil and Deuce.