Question

What is a sweeper?

Answer 1

Sweeper can be Physical or Special

Physical Sweeper
A Physical Sweeper is a Pokémon made to inflict massive physical damage, the fastest way possible. These Pokémon's stats concentrate on Attack and Speed.. Heracross, Tauros and even Charizard are good Physical Sweepers.

Special Sweeper
A Special Sweeper uses high Speed and Special Attack stats to blast its opponent with the strongest of special moves.. Alakazam is an example of Special Sweeper..

Hope it Helps! :)

Answer 2

Like J98 said, a pokemon with high attack or sp. atk and speed which means it can hit first and hard. it's a pokemon which it's main purpose is to "sweep" the opponents team by hitting going faster than the other team and OHKO or 2HKO them and fainting them one by one.

Answer 3

I think sweepers are pokemon with high speed and power means you might be able to knock out a pokemon in one shot