Guiding Questions:
1. How does this card stand on its own (analyze the HP, attacks, Abilities, etc. of the card)?
Terrakion has the all important 130 HP to survive Blue Flare and Bolt Strike, and as a basic, it can use Eviolite, making the chances of a Dragon KO negligible. Its retreat is abysmal, and since it's first attack is a two drop, getting the pokemon dragged out could be a serious problem.
2. What role does/could this card have in the metagame?
What has people talking about this card at all is its type advantage over big metagame cards like Zekrom and Magnezone. Terrakion one of the only cards in the format that can OHKO Zekrom, Magnezone, and the up in coming Zekrom EX. This can be very handy, and has basically have people thinking of this card as the next Bouffalant to shut down the highly anticipated lightning meta.
Here's the problem however, Terrakon is a two drop, and fighting pokemon have no real energy acceleration. Terrakion will almost certainly be out for one turn before it can attack, leaving it vulnerable to pokemon catcher. Smart Lighting users will do their best to drag it out if they can, and the card would be a lot better with a DCE. However, the card still has its uses, it can seriously hurt a deck with smart play, and the ability to OHKO so many important pokemon isn't anything to scoff at.
3. What cards, if any, does this card combo with?
Baby pokemon as bait could be a decent combo, or any other pokemon that has a low energy commitment so you can charge up Terrakion. Vileplume can override catcher, letting you set up Terrakion unmolested. Pokemon Catcher is a good combo card too, allowing you to KO any big electric pokemon after sacrificing a pokemon.
4. Give it a rating (out of 10), and explain why you have given it that rating.
I'll give Terrakion a 6.5/10. It might have more use with the release of Zekrom EX, (maybe even enough to warrant a 7/10 at that point) as snagging two prizes and killing a big main attacker might be worth the risk of investing the extra energy drop. It has uses, it's playable, and decks that run Zekrom EX or Magnezone should fear this card. It has enough going for it that careless play against Terrakion could have disastrous consequences.