>>18476130Mandibuzz is actually 2HKOed after rocks by LO Flash Cannon, and Aegislash can run speed EVs to outspeed Mandibuzz. The only surefire counter to Aegislash is Hippowdon.
Standard Rotom-W is 2HKOed by Crumbler sets after stealth rock (no, specially defensive Rotom-W is shit.) It's the poorest answer to Aegislash ever.
Also you might as well argue "I had Sableye and Terrakion on all my teams, I haven't had an issue with Mega Kangaskhan why ban it lol." I also have Mandibuzz on nearly all my teams, but I can still see that Aegislash has a detrimental effect on the meta.
Aegislash is just bulky, hits hard, has a million different sets, and has a unique typing that makes it an excellent counter to a lot of things. It's the #2 most used Pokemon in OU and SPL for a really good reason. If you don't think it's OP or at the very least an exceptionally good Pokemon, you're playing against shitters or you've purposefully built your team to not be weak to Aegislash.
