battle dome

[Vegeta rules]

I have already beaten the battle dome 6 or 7 times and I can't find the frontier brain I have only lost twice but when is it going to appear and I mean how times do I have to beat the challenge so it appears.

[Umbreon 1]

You need to go through the challenge five times in a row WITHOUT LOSING to face the Frontier Brain for the Silver Badge. You need to do it 10 times in a row to get the Gold Badge.