Transmitted archivelogs

select
  substr(local.name,1,50)  "Archive Name",
  case when remote.sequence# is null then 'NOT TRANSMITTED' 
                                     else 'transmitted'
  end,
  local.sequence#,
  local.thread#
from
  (select * from v$archived_log where dest_id = 1) local 
                                    left join 
  (select * from v$archived_log where dest_id = 2) remote
  on local.sequence# = remote.sequence# and
     local.thread#   = remote.thread#
  order by local.sequence#;

Applied archivelogs on primary

select distinct applied from v$archived_log where dest_id = &dest_id;

Applied archivelogs on standby

select process, status, sequence# from v$managed_standby;

Show messages

select message from v$dataguard_status where dest_id = &DEST_ID;