Question

because catching a patrat with your master ball is so much more important than them!

but seriously like no ultra, master, great, nest, etc.

Answer 1

Well you cant catch it for then so you have to defeat it. But afterwards you can go to the top of dragon spiral tower to encounter zekrom/rehisriam in again this time with pokeballs

Comments

can anyone support this? i want to know if its true

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Another way, is to defeat it. It will not disappear. It will disappear when you catch it. So check the rooms in the castle. There will be a Plasma grunt standing at a fireplace? I'm not sure about what it is, but he will transport you to the pokemon center. There you can buy some balls and there will be another grunt standing there to transport you back. That is in N's castle.

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Why commenting on such an old Q?

Answer 2

I can confirm this. Yes it is true; if you ''killed'' reshiram/zekrom at N's castle you can catch them later at dragon spiral tower. Tested on both B&W.