Inb4DarkSamusisoverpowered.
The thing with Dark Samus is that you need to know how to use it. I've seen players get killed extremely fast because they don't know how to recharge. Others know how to recharge, but fail to use the weapons properly and efficiently. Then there are those who mop the floor with other players' heads and destroy everyone long before the round is half over.
I have found that the Riflemen and the Juggernauts are good counters to Dark Samus, since it's health is so low. And always have Healers on hand, but never in combat. Keep them well away from any action and you and your team should survive the round.
As Dark Samus, keep away from Infiltrators and Gentlespies. They can and will kill you instantly if you stop moving. Recharge in mid-air, and often, especially after a large attack volley. The Shield is great for large groups of enemies. Get in the middle of them and use it. However, you are vulnerable to Infiltrators while you are charging the Shield.
You move extremely fast, especially in mid-air. Use this to swerve around the battlefield to prevent yourself from getting hit by Riflemen and Juggernauts.
Basic guide to Dark Samus right here. In the right hands, Dark Samus is unstoppable.