you missed the unburden part
and as an unimportant aside dark types aren't immune to haze as I doesn't target
yes belly drummers are especially weak to haze but you just don't throw them into battle the first chance you get, it's why most good teams with drummers have other set up that scouts...
it also isn't affected by intimidate and so is a better xern killer, and can run things like knock off, dual screens, rock tomb/twave, psych up, wide guard, snarl, trick room, and maybe even metal sound, safeguard and the cheesy double team
love this combo, and even though it's a relic of the past, this thing is so strong oml (can ohko zyg after spikes), there are plenty of ways to support this like sun + chlorotran core, trick room, or even some...