I "discovered" mandibuzz recently, and wow.
It's interesting to note just how defensive 'buzz is. Statistically, she's one of the best in the game before taking typing into account.
The top five pokes by combined defensive stats:
Giratina (150 / 120 / 120)
Cresselia (120 / 120 / 130)
Arceus (120 / 120 / 120)
Regigigas (110 / 110 / 110) Bleh...
Mandibuzz (110 / 105 / 95)
Regigigas isn't a defensive pokemon so he can fuck off. Giratina and Arceus are uber.
Mandibuzz has the second highest defenses in OU, a reliable recovery move that removes all three of her weaknesses, immunity to weather damage, great speed for a wall (taunting other support pokes and stall teams) plus whirlwind, tailwind, knock off and u-turn.
Why isn't she used more often? Lack of recognition? Sure, she's not gliscor/skarm and she has a stealth rock weakness, but she makes up for it with sheer bulk.
If she had spikes EVERYONE would be using her.