In my opinion, Metagross is not cheap(speaking of Garchomp,that's the cheap one), but still quite powerful. It has awesome attack, bulky defense and an okay speed to work with (can be boosted at the cost of a move slot, but i don't think it's worth it). Yet, as it has been mentioned, bulky waters like Milotic can beat it one-on-one even if Metagross has Thunderpunch (oh, and it doesn't help against the nr.1 bulky water - Swampert). Neutral special attacks are often good enough to faint him in two hits, if not OHKO.. and Fire Blast/Flamethrower are definitely instant-OHKO. Metagross is awesome to toy with, but nasty to play against.