Counter is Marth and Roy's Down B move in Super Smash Bros. Battle of Time
Marth or Roy will strike a pose and a small, metallic "chink" sound will be heard. For about a second, any attack that Marth and Roy is struck by other than a grab will turn them invincible for the duration of their retaliating swing. Marth's Counter deals up to 7% damage, regardless of the attack, while Roy's deals 1.5 times the original attack's damage. If the attack is a projectile (such as Samus' Missile), it will simply be deflected behind them and upwards at about a 30 degree angle. It's worth noting explosive projectiles can still explode and will still do damage if they are struck when the invincibility ceases. If the attack is a smash attack, then the attacker will be knocked back at a 90 degree angle. If used in conjunction with Mr. Game and Watch's Oil Panic, it is the most powerful non-charged attack in Battle of Time if Oil Panic has absorbed the most possible amount of damage, which is 250% damage and delivers a OHKO. It can be countered again for even more damage.
Marth's Counter has a faster start-up time and lasts slightly longer than Roy's Counter, which makes Marth's Counter more effective but less damaging.