Woah woah woah woah. Metagross is weak? I'm sorry but a pseudo-legendary Pokemon being weak is completely UNTRUE. I'm pretty sure you're going off on the basis of competitive Pokemon but even then, just one generation ago, Metagross was in OU. And the only reason Metagross is not in OU now is because of the MegaEvo completely outshining itself.
On a side note, the feeling of catching a Beldum is extremely satisfying. Just for that, I say take the challenge and go for it.