Still, the typing is terrible.
That's because it is one. Uninvested, it's defense is nothin' to boast about when you're 4x weak to the two most common physical sweepers' coverage/STAB types. It's laughably frail when it comes to takin' special moves as well. Aggron ain't a Bastiodon when it comes to defenses; and let's face it, Bastiodon is awful as well.