How do you get rubox in roblox?

If you're talking about PAX ( Pokemon Arena X ), that game has been removed for quite a while. But I still remember how to get Rotom ( Pokemon ), if I am incorrect in your means of "Rotom", then please edit my answer. To get Rotom in Pokemon Arena X, you have to wait until the game reaches Night, then go towards the Haunted House, you're able to see the Haunted House if you zoom out your screen. Then go towards the room with a TVand wait for a while. The TV will start to blink/flash. Rotom will then appear, it's quite difficult to touch it. So jump all over the Tv. Lol. Then you've got Rotom. If you're talking about Pokeblox, my bad, I never played that game. Answers are on YouTube and other different sites.