Steelix

Steelix makes for an excellent wall as it can sponge attacks from a large number of standards, can beat Metagross and most Tyranitar with STAB Earthquake, and can use the powerful Explosion to take out a threat. It can also phaze threats such as Snorlax and Baton Pass Zapdos while beating any Raikou that lacks Hidden Power Water; in other words, virtually all of them. However, it isn't used much because of its subpar offenses; base 85 Attack is not impressive at all, and consequently, quite a few standards take little damage from its attacks. It is far from unusable, though; it is one of the best BL Pokemon available.