>>150942423
take into account the following:
>pokemon, ghosts or not, get captured by pokeballs. captured pokemon can get captured again, this doesn't happen because most pokeballs themselves check IDs (mewtwo pokeballs do not check ids for example)
>spirit monsters are basically stands. they get ripped from their owners and sealed in stone. summoned monsters cannot be sealed away again, you need even more hax (paradox) and most sealed monsters kind of live in the spirit world anyway until summoned or bonded
so one method requires submission and the other is pure soul hax fuckery. there is nothing a ghost type pokemon can do to outfuck a shadow game duelist