It depends in what you need. Nidoqueen is a very strong special attacker with Sheer Force + Sludge Wave / Earth Power, and it has a decent bulk. Aggron on the other hand has a massive physical bulk and decent attack. If you see that by losing Nidoqueen your team will lack special damage, I would think about replacing a different pokemon.
This Aron is incredibly good. It has awesome IVs and an Adamant nature, and Aggron is definitely a good pokemon, with massive physical bulk, decent attack and level-up Heavy Slam and Rock Slide, so I would try to include it in the team. As a downside, you won't be able to get Head Smash in this Aggron, which is a real pitty since it's a 150 power STAB with no downsides due to Rock Head, but you could give it an ability capsule to get Sturdy and teach it Metal Burst instead so it's still good.