G'day, there was someone complaining of how difficult it is to do 3v3 arena when your server is just some months old and this player was suggesting bans for each team.
I don't know why the post is nowhere to be found but i'll just go ahead and try to help the future players in this situation.

Every lineup has a counter, blitz is no exception. Even though i agree adding a banning option for each team would be fun, there's no need, you just need experience fighting. Here are some ideas.

- Use Rin. Rin+any ninja with a mystery dodge passive will ensure your p1 survive at least 3-4 of the blitzing mysteries, potentially more if you have a pos2 or pos3 contributing to improve that.

- Use a p1 mystery unit yourself. For example, Edo Madara. This is the one i personally use, the second my Madara gets hit by a Kisame i get my CD reduction and cast him inmediately. Enemy pos2 blitz ninja won't even launch because i'm targetting it with my p1 Madara straight away.

- Use hit traps. What do I mean with this? Any unit that when getting hit creates a control debuff. You'd be surprised at the many times i used a p2 Summer Kurenai, recieved the Kisame blast with the shark combo & hiruzen with ignition combo and both ended up getting controlled, disabling the p2 blitz unit which allowed me to make my move and win the battle. If you don't have Summer Kurenai, you could use a 3* Rinnegan Sasuke. A S3xy Naruto. Edo Tensei Dan Kato.

- Debuff Barriers. Use buff neglecting barrier like Edo Madara's. Yeah they'll remove it with Kisame but who cares, their initial buffs are gone they won't hit you as much.
- There's a guy called Zetsu. Zetsu with BT can dodge up to 3 mysteries. With its resistance self buff good luck one-shotting that.

- Stack yourself up. Three earth main with aoe shield passive, with just a normal Konan if you use an akatsuki team, an Iruka if you use a konoha team, an Edo Sasori if you use an edo tensei team, or a Gaara for buffing wind p1 units will 100% guarantee your survival to those enemy blasts.

- Stack yourself harder. Shikamaru Chunin grats 100% def & res buff to secret jutsu units. Use him with Kushina and fire/lightning/water main and as soon as your mystery is up you will completely heal up any damage you've taken. Add a Summer Ino that also increases def & res by 100% aaaand yeah, laugh in the face of those blitzing lineups.

- Ninjutsu inmunity. While not effective vs Kisame or Kimimaro Halloween it's a great help against Edo Hiruzen, ninja that the previous two will usually have along in their lineups to increase their blitzing damage. Use Hashirama with BT, Tendo or Edo Madara with some other of the previous tips and you'll be able to do something with your teammates.

- P1 CC. Your initiative is lower than most of the enemy players you find because you're from a new server? Don't use your control ninja in p2, use it in p1. You may not stop the first blast but you'll block their second and therefore you won't die. I've been humilliated by p1 Ibikis more times than im willing to admit.

- Swordsmen. Lightning main has recently got a passive which increases Res by 100%. With some of the previous tips i'm sure you can build something that can tank & heal yourself. Take just a simple Hidan with breakthrough for example, they have to kill him.. what? two times? before he's really defeated? yeah not happening with the res buff and proper shielding.

- Hidden Mist. Use Mei with Chojuro & Mangetsu. Or Mangetsu & Edo Zabuza. Remember the swordsman res buff? Right. Mangetsu will make your fellow mist swordsman dodge something and whatever they don't dodge most likely won't kill them, from there the battle is under your control.
Taka Suigetsu makes a similar effect but im guessing is easier for new players to get Mangetsu first.

- Use Byakugou Tsunade. Obviously not a tip for new players, don't insult me just yet. Every time you get the chance to grab free frags of her from events do it. I'm no p2w and after many months saving up and grabbing free frags i've managed to complete her. Once you do you just stare at those blitzing teams, endure the blast and resurrect your team. Kakuzu Creation is also useful for that strategy, if you have a teammate with BT Six Path Naruto who can manage to at least kill a single enemy unit, your team will resurrect and you'll turn the tide of battle to your favour.

And that's all that comes to my mind, i'm sure there are veteran players around that can put on the table even more strategies to deal with blitzing teams.
Don't let those ruin your day! Open your ninja page and start giving your lineups a thought. I know newer players find it more difficult since your first touch with the game has been finding six path naruto, but back in my days everyone had to think in original lineups to make cool teams. You'll get used to it, this game is all about patience! Hope i could help a lil' bit