and custom post_types to custom menu

Try adding the action after the function like this:

function mt_add_pages() {
    // Add theme options page to the addmin menu
    add_menu_page(__('Competition','comp'), __('Competition','comp'), 'manage_options', 'mt-top-level-handle', 'test_func', '', 5 );
    add_submenu_page('mt-top-level-handle', __('Answers','comp-answers'),  __('Answers','comp-answers'), 'manage_options', 'sub-page', 'test_func2');
}
add_action( 'admin_menu', 'mt_add_pages' );