Basically, when you use the move Beat Up, depending on how many alive team members you have on your party, it will fire up a random base stat Dark Move equal to the number of team members. If one of your Pokemon has fainted and you use Beat Up out of 6 Pokemon total, it'll only fire 5 times due to that fainted Pokemon. The power of the Base Attack of each Beat Up strike has certain variables. From the actual Base Stat to STAB, to holding a Choice Band, they are all variables in the damage calculation of Beat Up. In theory, A Krookodile's Beat Up damage will do more damage than say, a Swirlix's Beat Up because of such factors. Say you want to figure out a calculation of how much a Pokemon's Beat Up's base power will be? As you saw in Bulbapedia, they provided this formula: Base power = (party member's base Attack) / 10 + 5. I'll provide an example. Say you want to find the Base Power of Sneasel's Beat Up. Input 95 for Base Attack, divided by 10 equals 9.5, +5 is 14.5. Even though Sneasel's Beat Up is 14.5 Base Power, this does not factor in STAB and items held.