DRAGON BALL Z: KAKAROT

The fight against Mira is only available after defeating all of the villainous parties in the game. You then have a fight with both Gotenks and Vegetto. afterwards you go to the land of Kai's. I suggest bringing Gohan,Goku, and Vegeta as they'll most likely be your strongest characters. Mira himself is level 100 and at this point I f you've been training and eating meals you should be as well. If you aren't then go get the recipe for the heavenly and super premium meals as well as the delexue meat meal. You want your Z and Meal community boards maxed. The fight at level 100 with Gohan is a cake walk especially if you have his sky dragon and limit breaker maskenko. At the start of the fight transform and just lay into him bring sensus if you need em.

Honestly, you can cheese the whole thing with Vegeta/Goku. I had Vegeta (80), with Goku (79) and Gohan (85) as support.

Make sure you have the highest forms of Big Bang Attack and Spirit Bomb available. For food, I just had the Deluxe Meat Meal, my cooking was only level 4, and Z-warriors were level 7, so those aren't particularly important aspects. Start the fight, immediately turn SSJ2, spam the hell out of Spirit Bomb (from support) and Big Bang Attack. Z-combos and Gohan's Super Kamekameha can give you breathing room if you need it.

The biggest thing is just paying attention to the boss's attacks. Repeatedly dodging to the side will allow you to avoid most of Mira's attacks. Dodging to the side of his Dark Kamekameha will give you plenty of time to charge Ki for more attacks.

It personally took me less than two minutes to beat him, and I used a single Senzu Bean (no other items). However, I would recommend a decent amount of healing items, depending on how confident you are at dodging attacks.

Finding Mira:
In order to fight Mira you must first complete all of the Villainous Parties. Afterwards, Mira will appear in "Land of the Kais" in the "Off-Earth Area". In order to reach this area and complete all of the Villainous Parties, you must have completed the story and I expect are around level 70-75. Personally I finished the story at level 70.

Preparing to fight Mira:
Here is the party I used to fight Mira.
Lvl 74 Vegeta --- Lvl 75 Goku --- Lvl 76 Gohan
There are 3 things that I recommend you have for the fight.
1. Healing items that can heal you for at least 300% worth of health, I used 2 Senzu Beans and around 5 Super Healade for the fight.
2. Self-medication Know-how for your character, in my case I had it on Vegeta (Acquired by clearing Lvl 5 in the training room)
3. Super Attack that deals stun and guard break damage
4. Any full meal. Personally I only used the first meal, and received the 22.5% health boost (the most important part) as well as a 22.5% Ki increase.

Here are my reasons for these three things, so you can decide whether you need each of them or not.

Reasoning:
1. Expect to take damage. It is definitely possible to do the fight without healing, but it will just be a bigger hassle than it needs to be. Chances are that you will have Senzu Beans that you didn't use like I did. In fact, after finishing the story and the Villanious Parties, I had 10 Senzu Beans that I hadn't used.
2. Self-medication heals you somewhere around 30-40% of your health over the duration of your Surge. I used Surge over 10 times during the fight, with Vegeta at level 74 with a 22.5% boost, he has around 9.5m health. That means that Surge healed me 30m+ health throughout the fight.
3. If you are around the same level as I was (75), the fight will be a long one. A huge part of making it easier on yourself, is making it easier to stun and guard-break Mira. Another bonus of these skills is that they can prevent him from acting throughout their duration. This means he has less time to attack or avoid you.
4. The main benefits of eating a full meal are the bonus to max health which will increase your recovery item efficiency, and the Ki bonus which will help you stay in Super Saiyan mode.

Fighting Mira
Lvl 100 Mira --- 56 Million Health
Fighting Mira is somewhat difficult, but in general is not too hard. The biggest reason for the difficulty in the fight is his level, his massive health pool and his high damage. At around level 75 expect to deal around 20k damage or so per attack. Throughout the fight you should always have Super Saiyan activated for the damage boost. My best option was Super Saiyan 2 for a 75% damage boost, which meant my damage was around 30-35k per hit. If you managed to reach this far with around the same level as I was, you will know that Ki based Super Attacks will only do 1 damage and are a waste to use. That means you are going to be smacking Mira for the whole fight... Yay...

After fighting him for a few minutes, his basic patterns should become pretty obvious. Do your best to evade damage, because each ability will generally do around 1m+ damage if the whole attack connects.

Mira's Attacks
Note that Mira can also perform normal melee and ki attacks, as well as the counter (bloody mist). Just make sure to use LT + X to evade the counter. If I don't write an answer to an attack, that means that the answer is LT + X (Invincibility Frames)

Android Punch: A fast punch that deals massive damage
Damage: ~1m per hit
Threat: High

Spirit Bomb: A massive energy bomb
Damage: ~300k per hit
Threat: Medium
Answer: Close Range / Medium Range = LT + X --- Long Range = Run to the side

Sonic Blow: A combo of punches and kicks
Damage: ~350k per hit
Threat: Medium

Dark Kamehameha: Always performs 2 in a row, except when interrupted
Damage: ~250k per hit
Threat: Low
Answer: Close Range = LT + X --- Medium / Long Range = Dodge to the side

Finish Breaker: Medium amount of rapid fire projectiles
Damage: ~50k
Threat: Very Low
Answer: Close Range = LT + X --- Medium / Long Range = Dodge (This is a great timing to charge Ki if you aren't too close to Mira)