You know what you're here for, you probably read the description for the achievement "Cat Scratch Fever".
The achievement itself might confuse some. The requirement is to win TEN TOURNAMENTS, not just matches, which some people might confuse. Basically you bet for a girl and she must win all 3 rounds for a count to be added.

With that out of the way, lets get on to useful tips.

You might have read this elsewhere but in case you don't know, the stars on the girl's stats represent how often or likely they will use a specific attack, though it doesnt mean they wil never use their weakest. I had plenty times where an opponent had 3+ starts on 2 of her stats and would use the third attack from time to time despite having only 2 stars.
Usually its safest to use the option that will either counter or tie their strongest attacks.
Try to alter in between 2 options, often times they will also switch around and you can land several succesful hits. When you get hit yourself, evaluate if its worth switching your past move or staying on it, its RNG at the end but on some situations using the same attack in a row can give succesful results.

Also, the color of the enemy attacks is important to pay attention to, if they only have a white aura initially, its worth to go for the most aggresive option, if they end up winning and only are able to do white-level damage, it'll be just a scratch, probably wont deal too much (unless you're low, hopefully it never comes to that)

Ok so beside the RPS RNG fest, button mashing is another part of the catfighting mode, its used on 2 situations:

• When you tie on your attack
  
• When you get a rainbow level attack for extra cheer damage

Having a turbo button can be useful here but BEWARE:
For real, its really dumb, I tried it myself and yeah its not worth it, actually what you wanna do is start mashing slowly and gradually increase, the AI seems to like to match your speed for these attacks, so if you configure a turbo button they will likely beat you every time.
After i turned that turbo off and i practiced a bit, I managed to find the perfect rythm of starting a slow mash to progressively increase to my maximum output, and I pretty much only lost 2 mashings from there onwards (thankfully they were white damage ones so i didn't suffer much).

Now on the contrary, you really, REALLY wanna get a turbo going on for the cheer button, after i enabled it i was doing consistenly so much more damage, in some situations where the opponent would still be left with some HP were i mashing manually, they would instead go down much quicker thanks to the aid of that turbo button, it will definitely make your life a lot easier.

I'll give credit where credit is due, thanks to this guide i learned how to enable the turbo, please check it out:
https://steamproxy.net/sharedfiles/filedetails/?id=2279316677

Ah well if you hadn't guessed for now, the best bet is usually Jennifer.
She's the best pick because you are basically removing the best "stats" from the roster by having her yourself. It's very likely that if you do not chose her, you'll encounter her on a 2nd or 3rd round (asuming she isn't the first opponent). Also her ability is great, you get yourself 2-3k damage on your opponent for free, and it activated for me more than 50% of the times, even if it doesn't she's strong anyway.

Now keep in mind that on the little bar on the bottom of the screen there will be some information that also might reflect the performance of the girls. Usually negative comments means they will perform worse.

If Jennifer currently has a bad effect you have 2 choices, either:

• Reload and it might be different, im not 100% of this because i remember before i was on Premium Adventure i reloaded my savefile like 4 times and lost always against Francisca on the 3rd round. However I was on PA when I actually got the achievement and I did a reload once after the one loss I got during the process and the whole tournament tree was different, so idk what's up with that
  
• Pick Momoko, i think she's the 2nd best girl and I used her when Jennifer felt like a weak pick for the current standing. Plus she has a heal ability (that if you also combine with the turbo will recover even more) so she can be a bit more tanky.

As said before you might need a streak of luck to achieve a full tournament victory, let alone 10, however they dont have to be in a row or anything, though you're free to reaload a save if you lose a match, if you care about the money.

Talking about money, ingame it says the higher your bet it might affect the winning odds, I have no idea if this is actually true but I would personally recommend you go for this when you're swimming on money either through business or after abusing Mr Shakedown for a couple of billions.

The max bet is 99 million so I'd say just bet all of that and then hope for the best using the tips I've described.

Hopefully you could find this guide useful and maybe with some of these tips more people might attempt to get the achiement lol, right now its sitting at 1% completion rate, tied at #4 for the least acquired achievement in the game, I can definitely see why.

If you got any feedback or stuff I might have wrong please comment bellow or let me know and I can fix it!

I'd say that with a lucky streak you can pull this off in about an hour to an hour and a half. I had 0 progress done and got only 1 loss on my process for getting it, and I got motivated to write this to share some of the little tips i developed.

Anyway, good luck and happy hunting!