Thanks to Regenerator and its amazing bulk Amoogus can often switch in to a powerful attacker to scout its move, take it, and switch out a Pokemon which can take it. An example I can think of right is something like vs Choice Band Dragonite. While Dragonite can easily 2HKO even physically defensive Amoonguss, however, using this information you can switch to another Pokemon to what it used: Fire Punch -> Heatran or Earthquake / Outrage -> Skarmory for example, all while Amoonguss its self helps back a good chunk of its own HP just by switching out.And could you explain Amoongus as a pivot to me? I really want to try it but I can't figure out a good set to run on him, and he's countered me so many times...
This isn't even just choice band users, but Amoonguss can also scout out Pokemon sets and put an emergency stop with Spore. You can even mess with people and switch it around on resists, to stall out, if you are in otherwise a losing situation.
I use a Physically defensive set personally with Spore / Giga Drain / Sludge Bomb / Hidden Power of Choice. I support Clear Smog might be an option in the last slot for stall, but I haven't seen much use for it in the current meta, Stun Spore is poo on stall.