"he didn't die in the first place
alamos town was TELEPORTED to the dimension of space sooo...... darkrai was too
alamos comes back..... so does darkrai"
Darkraid did die, just not in a violent way. The town being "teported" to "another dimension" was a way to indirectly refer to death.
In DBZ, the first part of the dub had people going "to another dimension" instead of being killed. Those were dub edits since kids shows can't have words like "death".
"now what is "shadow realm"?"
The shadow realm was an dub edit for dying. In Yugioh, if you lose a shadow duel, you die.