Beat Up deals damage from each Pokémon on your team that does not have a status ailment (nor is fainted). Each strike has a different base power, calculated as:

However, the actual attack is carried out by the original user of Beat Up, so it will always use that Pokémon's current attack stat to calculate damage. It will also receive any boosts from the originating user, such as STAB and any applicable items. However, any items held by the rest of the team do not affect the damage dealt.

Each strike of Beat Up is treated like a separate attack:

The move Counter only counters the final hit, but Bide counters the complete damage.

Let's say we have the ultimate team of 1 Weavile and 5 Magikarps. One of the Magikarps is paralyzed, so only 4 can attack with Beat Up. Weavile's base Attack is 120, while Magikarp's is an incredible 10. Beat Up would attack 5 times, first with 17 base power (120 ÷ 10 + 5) and then 4 times with 6 base power (10 ÷ 10 + 5). The result would be as if Weavile had attacked with a Dark type move of 41 base power.

In a more realistic scenario, the average total base power for Beat Up is typically around 60-90.

When a Pokémon is holding Darkinium Z and uses its Z-Power, Beat Up turns into Black Hole Eclipse and has base power 100.