drift

@using Umbraco.Core.Models;
@using Umbraco.Core.Services;

var contentService = ApplicationContext.Current.Services.ContentService;
var contentTypeService = ApplicationContext.Current.Services.ContentTypeService;
var contentType = contentTypeService.GetContentType(4200);

var content = contentService.GetById(2052);
content.ChangeContentType(contentType);
contentService.Save(content);

drift

@using Umbraco.Core.Models;
@using Umbraco.Core.Services;

var contentTypeService = ApplicationContext.Current.Services.ContentTypeService;
var contentType = contentTypeService.GetContentType(4200);
contentType.ParentId=3130;
contentTypeService.Save(contentType);

drift

        var contentService = ApplicationContext.Current.Services.ContentService;
        var content = contentService.GetById(1538);

        //quick change lots of nodes template
        var fileService = ApplicationContext.Current.Services.FileService;
        var template = fileService.GetTemplate("CJ-Content"); 
        foreach(var item in content.Children())
        {
            item.Template = template;
            contentService.Save(item);