same thing

As we know shadow is an assasin you will see him again in some pub in some city or town but you must pay 3,000gil to be in your party again....(try it!!)

i dont know

If you're in the world of ruin, I know a way to get him back. You have to find in sum fighting place and you will have to fight him. It was easy to do.

The only way to get him back is to either go to that island when the empoeror sent you or if your doing floating continent it's easy, you talk to him, he will join your party =D

By the way, go to gamefaqs, they tell you what/where/name of the fighting place is.

If you are in the WOR and you don't see Shadow's pic when you go to a weapons shop that
means you didn't wait for him on the Floating continent and cannot get him back. If
you're in the WOB just wait till you get to Koligen, he'll be in the pub, or wait till the
emmporor hires you to help him, he hires Shadow too.

And if you're in the WOR go to the cave on the Velt and you'll find him. Then go to the
colisium and bet the Itchigeki, it's in the cave on the Velt, and you'll fight him and get
him back.

on the floating continent b4 u jump on the airship (after you defeated nelapa) WAIT UP
UNTIL THE LEFT TIME IS 00:05 THEN HE WILL JUMP UP AND JOIN YOU AGAIN