Professionally speaking, when someone requires a translation into Latin American Spanish, what they are basically asking for is what we would call a Neutral sort of Spanish with the least number of local expressions. A language completely void of any regionalism that might sound strange in any specific Latin Amercian country though it would include certain vocabulary that would not be accepted in Castilian Spanish.
Neutral Spanish is a flavour that specially applies when doing voiceover for soap operas. The closest actors using Neutral Spanish sound like is Mexican Spanish, but this is very subjetctive ...
