Ok.. so you are going to show your O.C., and what does each Mane-6 get from them.

Heath
let's say that by default, most have 5 heath

Attack (2/3 to hit)
let's say that by default, when you count all of the ones that the mane 6 have, most will be 21
( most of the time: 2, 3, 3, 4, 4, 5)

Defend (1/3 to block)
let's say that by default, when you count all of the ones that the mane 6 have, most will be 11
( most of the time: 1, 1, 2, 2, 2, 3)

Lets try to have each O.C. with the same Valu
each Heath point = 2V
each Attack = 3V
each Denfend = 1V
(2 X 5) + (3 X 21) + (1 X 11) = 10 + 63 + 11 = 84
each O.C. should have a Valu of 84

Each Mane 6 starts at there "house"
Pinkie Pie at SugarCube-Corner
Twilight Sparkle at the Library
Applejack at Sweet-Apple-Acres
Fluttershy at her Cottage
Rarity at Carousel Boutique
Rainbow Dash at ... Open-fils ?

You start with your Elements of Harmony
and pick up 3 random O.C. cards, but you only keep 2 of them

you walk around, going to the different places, picking up 2 Carts at each place, but only keeping one of them (p.s. you can't go to the last 2 place you went)

When you bomp into an other play, you 2 have a Fight,
you each pick one O.C. to fight with, the play who's tear isn't goes first
you roll the number of Dice = to what the number that this O.C. gives to this Mane 6 for Attack, if you have a 3 or higher it's a hit
the other play rolls the number of Dice = to what the number that this O.C. gives to this Mane 6 for Defend, if you have a 5 or 6, that blocks an attack
do this back and forth until one O.C. is out of Hearth,

the Loser gives her Elements of Harmony to the Winner, and the O.C. they lost with (if you don't have an Elements of Harmony, give on other O.C. of your choice)

When one player had all 6 Elements of Harmony, they get Crown the New ruler of Equestria

https://sta.sh/0muszq5xjsz

FlashTruth

Heath
6

Attack
T.S.: 6
R.D.: 2
A.J.: 3
P.Pie: 3
F.S.: 3
Rarity: 3

Defend
T.S.: 2
R.D.: 2
A.J.: 2
P.Pie: 2
F.S.: 2
Rarity: 2

(2 X 6) + (3 X 20) + (1 X 12) = 12 + 60 + 12 = 84

Farmer

Heath
6

Attack
T.S.: 1
R.D.: 1
A.J.: 6
P.Pie: 3
F.S.: 5
Rarity: 2

Defend
T.S.: 3
R.D.: 3
A.J.: 4
P.Pie: 2
F.S.: 4
Rarity: 2

(2 X 6) + (3 X 18) + (1 X 18) = 12 + 54 + 18 = 84

A-Dark-ble

Heath
5

Attack
T.S.: 4
R.D.: 2
A.J.: 3
P.Pie: 2
F.S.: 6
Rarity: 3

Defend
T.S.: 2
R.D.: 1
A.J.: 3
P.Pie: 1
F.S.: 4
Rarity: 3

(2 X 5) + (3 X 20) + (1 X 14) = 10 + 60 + 14 = 84

DERPY

Heath
1

Attack
T.S.: 4
R.D.: 4
A.J.: 4
P.Pie: 4
F.S.: 4
Rarity: 4

Defend
T.S.: 2
R.D.: 2
A.J.: 2
P.Pie: 2
F.S.: 2
Rarity: 2

Light Heart

Heath
6

Attack
T.S.: 6
R.D.: 4
A.J.: 3
P.Pie: 4
F.S.: 2
Rarity: 2

Defend
T.S.: 1
R.D.: 1
A.J.: 2
P.Pie: 2
F.S.: 3
Rarity: 2

(I don't know if I did this right.)