"Dude, that's so meta."
Meta is a prefix, derived from ancient Greek, used to indicate concurrency and reference. Metadata is included with your data and describes aspects of the data while remaining separate from the data itself.
"Yo, bro, that's gross."
Gross is a word descended from Latin, through French, and into Middle English that originally meant large. In current English "gross" is no longer used this way and instead means a collection of twelve dozen (144) items.
Who is the heaviest of all the Pokémon? Not Wailord. Who is the brilliant mind trapped in a bulky body made for battle?
"Dude, that Metagross is huge, bro."
I like to think of Metagross as exemplifying the concept of the "ghost in the machine." Metagross is both the sum of pre-evolved forms (two Beldum make a Metang, two Metang make a Metagross) and something more - a mind inside the metal frame. I believe that it manifests its psychic nature from something more than just the cords and wires that make up its computer brain.
Metagross weighs 1212.5 lbs (12 X 12 = 144, get it?) because he is all metal. I just want to put this right up front because our pal Metagross takes normal damage from Fighting-type moves and is particularly susceptible to Low Kick - a Fighting-type attack that gains power the heavier the recipient is. Keep in mind the Fighting-type Pokémon that can learn Low kick and be wary if you come across one in battle. Grass Knot is not as much of a concern since Metagross only takes half damage from Grass-type attacks.
I have tried to use Metagross competitively and will try again once I figure out the best way to add it into my team. Its stats add up to 600 with an emphasis on the physical - Attack and Defense - which can be tricky when you are focusing on Psychic type attacks. Speed and HP are particularly low with the Specials right in the middle. Natures to look for include Adamant or Naughty to build up Metagross as a physical attacker or Impish or Lax to build it up as a physical defender. I do not recommend Brave or Relaxed natures as I always worry about sacrificing speed.
I have been considering a new framework in developing move sets for dual-type Pokémon. I think it is best, when possible, to include two power attacks that leverage STAB, one attack that targets a particular weakness, and a status move. A potential move set for Metagross includes Meteor Mash and Zen Headbutt (taking advantage of STAB and the physical Attack stat), Earthquake to combat super effective Ground and Fire-types, and Agility to help get Metagross's speed up if possible.
When thinking about hold items, I would recommend a Ground Gem as a defensive maneuver. This way when you use Earthquake against a Fire or Ground-type you may have a better chance of knocking out your opponent.
If you can get a Metagross with the Light Metal ability stick with that. This halves Metagross's weight so that Low Kick becomes less effective.
Last week my competitive session at the Red Room at the Black Cat in DC was highly successful - no one showed up but I sampled some excellent beers! I'll be back again this week to see if I can find any more challengers (and I may just be using Metagross)!
I was thinking this evening that I wanted to add something more about Metagross's catch rate.
Metagross has an equivalent catch rate to the legendaries - that is to say, the lowest at 3. I can't say I am a pro at explaining catch rate; I do know that the starting part of the formula is the catch rate divided by 255. Nosepass has a catch rate of 255, which starts him out at "1." Metagross (and all of its prior evolutions) starts the formula at 0.01176470588235. Now, to catch a Pokémon, you have to get the formula up to 1 or above (by reducing health, inflicting status conditions, etc. - you know, you've caught a Pokémon before). So it should be extremely difficult to captutre a natural Metagross. Be very wary of the bro (or sistah) who shows up for battle with a shiny Metagross.
What makes catching a Metagross even more intriguing is that, unlike legendaries, it doesn't hang out in one place. You actually have to be lucky enough to encounter a Metagross before you can even begin to manipulate its catch rate. I think that makes Metagross the hardest Pokémon of all to catch!