所以我想知道是否有任何方法可以获取用于register_post_type 对于插件生成的帖子类型，这样就不必使用插件了？

您可以使用get_post_type_object( string $post_type ). 请参阅文档和示例用法here.

$obj = get_post_type_object( \'certification\' );

print_r( $obj ); 

stdClass Object
(
    [labels] => stdClass Object
        (
            [name] => Certification
            [singular_name] => Certification
            [add_new] => Add New
            [add_new_item] => Add New Certification
            [edit_item] => Edit Certification
            [new_item] => New Page
            [view_item] => View Certification
            [search_items] => Search Certification
            [not_found] => Not found
            [not_found_in_trash] => Not found in Trash
            [parent_item_colon] => Parent Certification:
            [all_items] => All Certifications
            [menu_name] => Certifications
            [update_item] => Update Certification
            [name_admin_bar] => Certification
        )
    [description] => Certifications
    [public] => 1
    [hierarchical] => 1
    [exclude_from_search] => 
    [publicly_queryable] => 1
    [show_ui] => 1
    [show_in_menu] => 
    [show_in_nav_menus] => 1
    [show_in_admin_bar] => 1
    [menu_position] => 5
    [menu_icon] => dashicons-welcome-widgets-menus
    [capability_type] => post
    [map_meta_cap] => 1
    [register_meta_box_cb] => 
    [taxonomies] => Array
        (
            [0] => objective
        )
    [has_archive] => 1
    [rewrite] => Array
        (
            [slug] => certification
            [with_front] => 1
            [pages] => 1
            [feeds] => 1
            [ep_mask] => 1
        )
    [query_var] => certification
    [can_export] => 1
    [delete_with_user] => 
    [_builtin] => 
    [_edit_link] => post.php?post=%d
    [label] => Certification
    [name] => certification
    [cap] => stdClass Object
        (
            [edit_post] => edit_post
            [read_post] => read_post
            [delete_post] => delete_post
            [edit_posts] => edit_posts
            [edit_others_posts] => edit_others_posts
            [publish_posts] => publish_posts
            [read_private_posts] => read_private_posts
            [read] => read
            [delete_posts] => delete_posts
            [delete_private_posts] => delete_private_posts
            [delete_published_posts] => delete_published_posts
            [delete_others_posts] => delete_others_posts
            [edit_private_posts] => edit_private_posts
            [edit_published_posts] => edit_published_posts
            [create_posts] => edit_posts
        )
)