Yup, there is a heads up on the arena.. It is very difficult and may require leveling up cutie marks to come up with a strategy to defeat all 7 bosses. I hope you enjoy it.. Took forever to make this lol
Anyways, patch notes!:

• Battle arena is now avalible
  7 superbosses will be waiting for you for a challenge!

• Nerfed Zero Storm (No longer attacks twice per hit)

• Updated Tiger Stance’s description to tell you what it actually does

• Strong Attack costs 15 TP

• No Shadow Kick should work better now

• Cherry Blossom is fixed, but now costs 65 MP

• Dragon Breath now costs 99 MP

I hope you enjoy the arena everyone! And, don’t forget to read the text file explaining how to transfer saves between versions if you’ve played previous versions!!

Well, that’s all I have to say for now. Enjoy this update and have a nice day!
~Nurse Dashie