For the v2 of WP REST API use this format-
http://demo.wp-api.org/wp-json/wp/v2/posts?include[]=470&include[]=469
If you want custom coding then,
You can retrieve single post by id like
http://demo.wp-api.org/wp-json/wp/v2/posts/?filter[p]=470
But as per support its will not work for multiple post.
https://github.com/WP-API/WP-API/issues/1368
So you can ran a loop and get one by one.
But for multiple you have to put an function
add_filter('rest_query_vars', 'custom_rest_query_vars');
function custom_rest_query_vars($query_vars) {
$query_vars = array_merge( $query_vars, array('post','post__in','type','id') );
return $query_vars;
}
Then you have to run
+filter[post__in][]=470&filter[post__in][]=469