How often do Rainbow Puddings drop

I found the solution. I have to cast slow and berserk on it, so that it can't use "thermal ray".

It was so obvious... How do I forgot?

Thank you again.

Taken from the FF Wiki:

The original SNES version of Final Fantasy IV (Final Fantasy II in North America) and its PS1 ports contain a simple exploit that allows the player to duplicate any item that can be equipped in either hand.

The player must make sure there is at least one blank space in the party's item inventory.

The player must equip any character with a weapon or shield item they want to duplicate.

Enter battle.

When the chosen character's turn comes up, the player should choose the Equip command, and select the blank space in the inventory and trade it with the item one wants to duplicate.

Without exiting Equip mode, one must select the item again, and trade it back into the equipment slot from which one removed it in the previous step. (note: this step is skipped entirely in the demo video; the character instead defeats the monsters with magic after unequipping the weapon, then step seven is "re-equip the weapon you wanted duplicated from the menu screen.")

Win or flee the battle.

On the Main Menu, the player can check the character's equipment. The character will be holding two of that item.

The player can then move the doubled item into the inventory, then re-equip it. Since the character can only hold one, the other will be left behind in the inventory.

Each character that begins the battle can use this bug to duplicate the items in both hands, but it works only once per battle, and only with the items equipped when the battle begins.

This bug could be exploited to multiply unique weapons like the Crystal Sword or Gungnir spear, making them practical as ammunition for Edge's Throw command. This would also allow Edge to equip two Masamunes.

This glitch does not work on arrows.