This is very similar to this question on how to add class to select2 element, however the answers there appear to target earlier versions of the framework which has undergone so
Found a way to add a class. had the same problem couldnt find a way and made it myself, so here it is:
$('.select2').on('click',function(){
var matchBlock = $(this).prev();
if(matchBlock.hasClass('select-control-left')){
$('.select2-dropdown').addClass('blue-select');
}
else{
$('.select2-dropdown').addClass('orange-select');
}
});