Not withstanding Remedial Goodness 101, Grammar is the fifth period class for Mal (according to Mal's Diary) and the third period class for Evie and Jay. Once again it is not known which class number it is for Carlos, but considering that Mal, Evie and Jay all take Grammar and Grammar is needed in all places one can determine this a core requirement and as such would be on Carlos' class list.
Descendants: Mal's Diary
In Mal's Diary she lists her schedule (for her first semester) it is
History of Woodsmen and Pirates
History of Auradon
Safety Rules for the Internet
Remedial Goodness 101