Awesome, we get to review one of my favorite cards of all time.
1. How does the card stand on its own? Is it good, bad, or it has potential?
On its own, Gyarados can be very good. Put techs like Sableye and Regice and this thing is sure to cause havoc upon the opponent. Gyarados on its own also takes down Donphan easily. The ability to hit for 90 damage, or 110 damage if there's expert belt, for no energies makes this card very good.
2. What popular metagame decks is it used in?
It's basically often runned on its own. As mentioned earlier, every Gyarados will often run 4 Sableye to guarantee a start with this Pokemon so that they can use Pokemon Collector, a Supporter that greatly benefits Gyarados, on the first turn, and there'll always be at least 1 Regice to move your opponent's Pokemon around, mainly for Spiritombs and Mr. Mimes, as well as helping to discard magikarps. Of course, a Gyarados deck will also often use usual support like Uxies and Azelfs as well, and maybe Claydol too. In fact, in many Gyarados decks, you won't even need to run Claydol due to cards like Felicity's.
3. What combos can you use it with? How so?
Well really, as it has been mentioned earlier, definetly it would be Sableye and Regice. For me? Well, I would often like to put Crobat G and Poketurns in order to do extra damage in order to make Tail Revenge a much more powerful attack. I can also consider Luxray GL Lv. X. Sure you have Regice, but you can use Luxray GL as a tech in order to take down certain cards you want to KO, such as Claydol.
4. Give it a rating, and explain why would you give it that rating.
Overall 5/5 in modified. This card is one of the 4 biggest contenders for states, along with Luxchomp, Cursegar/Spiritomb, and Dialga/Garchomp. The ability to hit for 90 or 110 for no energy is very good. Sure Luxray GL and Spiritomb may hinder it (Spiritomb because of the fact Gyarados relies on trainers), but Gyarados can do well against many other decks, especially when it comes to Donphan, which is probably its easiest matchup. Gyarados is a card you shouldn't laugh at, because it is one monsterous attacker. No wonder it is called the Atrocious Pokemon!
5. How 's the artwork?
I must say, that probably has to be one of the best Gyarados artworks I have ever seen. It really looks as if Gyarados is in a total rage. Seriously, Midori Harada is such an amazing artist. I think this has to be one of his best Pokemon drawings.