I accidentally knocked out Cresselia; can I bring it back?

Question

I killed it and I don't know what to do! Please help! Edit: the game I have is Pokemon diamond

Comments

Which game?

---

If OR/AS, it comes back, (don't remember how), if US/UM, it will still be encounter-able in the Ultra wormhole until you catch it.

---

There should be some way to battle it again in every game except Diamond and Pearl.

---

read description

---

That was an edit made after the comment

Answer 1

Unlike in later games, such as Platinum and HeartGold/SoulSilver, there is no way to respawn a legendary if you flee from it or knock it out. Thus, in Diamond and Pearl, you only have one shot to catch each legendary Pokémon, and you must capture either Dialga or Palkia respectively to advance.

Source

Comments

i voted this question because i didn't know this was a thing in diamond/pearl, and i thought it was useful info

Answer 2

If you saved then it is too late, but if you haven't yet, soft reset (l+r+start). Then you can try to find it again

Comments

According to whom? In many games, beating the Elite Four again will cause knocked out legendary Pokemon to reappear. OP didn't mention their game -- clearly you can't know this for certain.

---

well I killed it a long time ago.