Config.php and pollers

Do changes to config.php need to be mirrored to all pollers or does the librenms server config.php file effect all pollers?

ie if I disable ospf polling on the server config.php does the poller get upadted not to poll ospf?

Do pollers even need a config.php?

Pretty much yes, mirror config.php to all pollers. You could set settings within the database to avoid that for some things.