Undefined property: WP_Query::$post

First of all post field of WP_Query is current post ID and not post object. But I don’t think you should use it before calling the_post() method.

Normally you should do it in this way:

$args = ...
$hometeams = new WP_Query( $args );
$teamishome = $hometeams->have_posts();
while ( $hometeams->have_posts() ) {
  $hometeams->the_post();
  $scorehome = get_post_meta($post->ID, 'report_homescore', true); // you want only one meta, not all array I guess.
  ...
}