>>31202383http://www.smogon.com/smog/issue18/stallbreakersGenerally what makes a stallbreaker is either:
A) Preventing them from healing and/or statusing while being able to do so yourself.
B) Having an immunity or otherwise ignoring status effects like Toxic.
Then you proceed to setup. Since stall often relies on indirect damage from status effects and field hazards instead of directly attacking you, anything that abuses that is capable of dealing with stall. Things with Magic Guard, Magic Bounce, and Taunt are good for that purpose, provided they aren't super frail.
Alternatively, you can use an all-out mixed attacker with good coverage and high attack stats, or special attackers with Psyshock and a setup move. The downside to this is that they can still recover and status you, so you really need to be able to 2HKO them or better.
Stall is still hard to deal with even if you're prepared for it, and if you over-prepare to make them easy you suddenly are at a disadvantage versus more offensive teams.