Counter

Counter is the down special move of several playable Fire Emblem characters. It is first used by Marth and Roy in Super Smash Bros. Melee, by Ike in Super Smash Bros. Brawl, by Lucina in Super Smash Bros. for Nintendo 3DS / Wii U, and by Chrom in Super Smash Bros. Ultimate. Each fighter capable of using Counter can use it in every Super Smash Bros. game that they are playable in.

The move is based on the combat of the Fire Emblem series; when one unit attacks another unit, the opposing unit counterattacks afterwards. Before using Counter, the fighter enters a readied stance, and if they are attacked by an opponent, the fighter automatically counterattacks, reflecting all damage and knockback back onto the opponent. If a character is in their readied stance for too long, their Counter becomes ineffective.

Marth
In Super Smash Bros. Melee, compared to Roy's Counter, Marth's is faster and lasts longer, but only deals a set 7% damage no matter the attack. In Super Smash Bros. Brawl and Super Smash Bros. for Nintendo 3DS / Wii U, however, Marth's Counter deals 1.1 times the damage of the opponent's attack.

In Super Smash Bros. for Nintendo 3DS / Wii U, the first custom variant for Marth's Counter is Easy Counter, which has a longer window for counterattacking but deals less damage. The second variant is Iai Counter (known as Rush Counter in the PAL release), which deals a faster attack that sends the opponent flying behind the player, but does not deal as much damage.

When Marth uses Counter, he says "Soko da," which translates to "There it is." This means he has found an opening to attack, and there it is.

Roy
In Super Smash Bros. Melee, Roy's Counter deals more damage than Marth's, inflicting 1.5 times the damage the attack would have dealt. In Super Smash Bros. for Nintendo 3DS / Wii U, the multiplier has been decreased to 1.35 times the damage.

Ike
Ike's Counter has greater range and deals greater damage than Marth's Counter, inflicting 1.2 times the damage of the opponent's attack, but like Roy's is slower.

In Super Smash Bros. for Nintendo 3DS / Wii U, the first custom variant for Ike's Counter is Paralyzing Counter (spelled Paralysing Counter in PAL regions), in which the attack stuns enemies rather than damaging them. His second variant is Smash Counter, which is slower but deals increased damage and knockback.

Lucina
Lucina's Counter operates identically to Marth's Counter, dealing 1.1 times the damage of the opponent's attack. In Super Smash Bros. for Nintendo 3DS / Wii U, the custom variants for her Counter are also identical.

Trivia

 * Lucario's move, Double Team, is very similar to this move, the difference being the damage dealt is effected by Lucario's damage percentage.
 * According to Masahiro Sakurai, each Fire Emblem character's Counter move is meant to reference the turn-based elements of the Fire Emblem series.