A lot of people in this thread are missing the point.
Stalling teams and stalling Pokemon are based on different principles, though stalling teams always include some form(s) of stalling Pokemon.
Bronzong is not a good staller because in most cases if he does not have a move that hits his foe super-effective, he won't outlast them. A lot of things, particularly Pokemon with Close Combat and special attacker dealing neutral STAB damage, can easily come in and 2-3hko, taking piddly damage from whatever attacks he may be packing (at the max two different ones, as Rest/STalk take up the half a moveset). Far too many things can even set up Subs on Bronzong, as it doesn't have Taunt either. So Toxic may not even do it.
In short, there are too many things that can switch into Bronzong without fear and
outlast it, effectively outstalling "the Premier Staller of D/P".
A true stalling Pokemon can waste the enemy's turns and mostly sustain it's health without having to switch out to get Wishes passed to it, a trait that Bronzong cannot boast. It also should have some way to encourage the enemy to switch out so that they take some spikes damage or allow the staller to status another member of their team. This could be by indirect damage like Toxic, Sandstorm, or Leech Seed, or more direct attacks. Stalling Pokemon should also not have to largely rely on typing to keep their enemies at bay. If I switch Weezing into something like non-SE Heracross and proceed to Pain-Split it repeatedly for 10 turns and throw in a T-bolt when I can, refusing to faint or let Hera past, that is not stalling. That is
walling, using type to stop things in their tracks. Bronzong cannot continue its "stalling" if, say, Infernape switches in, despite the fact that it can wall many metagame standards and threaten them with 4xeffective moves.
Good stalling pokemon are things like Subseeders, PP stallers, and even Flinch-Haxers kinda. Here's an example from the Anaylses Section.
Aerodactyl
name: PP Staller
move 1: Substitute
move 2: Protect
move 3: Roost
move 4: Fly/Rock Slide/Earthquake/Aerial Ace
item: Leftovers
ability: Pressure
nature: Jolly
evs: 252hp/6spdef/252spd
It's not screwed if something with super effective damage comes in. It can't really be put to sleep. It can only last so long, but it's longevity is not determined by it's typing or defensive stats. Same deal with things like Sceptile and Jumpluff. These are the real stallers.
Stalling teams have the same goal as these individual stallers: to waste turns, deal a large amount of indirect damage, force switches, and outlast the enemy. They just take a more teamworkish stance towards things. They rely on many sturdy Pokemon to ensure a solid defensive framework and then use actual stalling pokemon like SubSeed Breloom to shuffle through teams and wear them down. Stalling teams often utilize statuses like Will-o-Wisp and Thunderwave to weaken the opponent's offensive abilities and better their chances of outlasting.
That was long.