G2 boats are easily defeated in a 1v1 match... no one will refute that. But the problem is when places in multiple times or even with other ships, they will be able to deal almost as much damage as a K-XCA in the 30+ ranges with very minimal charge. While this means nothing in a 1v1 because you can simply reinforce, it means in a 2v2 or a 3v3 that if you have a plasma boat, or Fed/Lyran bent on close combat, that hydran will basically dish out damage while keeping a safe distance.
Another flavor to the cheese is that, sure, the 2 or 1 ships engaging the 2 or 3 ships will die, but not without someone/two else dead/on the verge of dead, if played right. Many people consider this playing right to be a strategy, but it really isn't. You basically run. There is no refutting strategy to it. You run with G2 and only G2s on while your friends tank (this includes other X phasers off), constantly doing quadruple upon quadruple 20+ G2 fire. Why go 30+ when your friends are taking the damage, but keep that safe distance, because you won't increase much anyways. And if they are beginning to cripple, run into them, and bam. To top it off, they come with 6 fighters. The only way you can lose to a G2 Boat on a team battle is if they have G2 boats, or if your teammates are a little slow... or perhaps you are. No offense. And by this, I mean those that come with 4 G2s. Not the H-XCB or H-XCA or the Light Cruisers (although the LCs seem to do well, it is only on predictable opponants... pick up a STL or a Dread and see how you fare :-) )
In no way are the G2 Boats strong in 1v1... they are actually extremely weak in a 1v1... you can easily negate their firepower with reinforcements. But their power in teams is the rapid and nearly continuous *1 round per charge* shots of the G2... of course while your tanks keep their excess energy down with weapon fire. It hurts...
All in All, I would like to say G2s are balanced because of their easy defeat in a 1v1, but most people simply don't 1v1, so... it does become a problem. I know, I used duel H-XCFs in the last Tourney... It was utter ownage for us. I in no way consider that skill. My partner just said to do it, and I thought it would be hilarious. Anyways, I hope this helps, gl.