If it needs to be overpowered or funny:

Sig attack: Super Smash arts- Wario Super technique
Description: user throws a Bob-omb at the enemy,turns around and uses the "wario waft/nuclear fart" seen in the trailers for Super Smash Bros: Brawl, exploding the bomb and sending the enemy flying. The enemy then flies into a wall, and the user of this sig then rams the enemy.
Effect: 4 hit attack [50 fire dmg + 100 wind damage + 2x 50 null dmg]
Cooldown: Still figuring that one out




One that might work, and that I actually like, a counterattack:

Sig attack: Evade and attack
Description: dodges an attack by an enemy, and then retaliates with the users signature weapon. If they don't have one, they attack with a sword.
Effect: (passive) Whenever the user dodges, they have a chance for the mod to decide to allow it to hit. The chance starts at 5%, the next dodge that turn becomes 10%, the next 20%, and every dodge that turn after that has a 40% chance. However, the user's dodge must be successful for the "Evade and Attack" sig to work.
Example:
Turn 1
1) Dodge
2) Dodge
3) Dodge
4) Dodge

Enemy A attacks and misses due to the first dodge, so "Evade and Attack" has a 5% chance of initiated. EnemyB attacks and misses, raising the chance to 10%. Enemy C actually hits, canceling this. Enemy D attacks and misses, so "Evade and Attack" has a 5% chance. The damage is a set amount plus x per level.

Impractical and implausable to add... oh, well.

Another sig attack that is overpowerred:

Cybeast fusion
Description: fusing with a cybeast, the user becomes heavily armored and enters a "BeastOut" state. This is different from a BeastOut or BeastOver in that instead of the cybeast being absorbed, the cybeast willingly fuses with the user.
Effect: Adds extra HP meter and gives extra attacks. If Cybeast HP is destroyed, user returns to normal, but with a stun-like status that lasts the whole battle. If the user's HP is targeted, the Cybeast HP may take the damage to its HP. Also, the user is given extra attacks that it can only use in Cybeast Fusion form, such as an attack that does low damage but is impossible to dodge, or a special attack that can only be used by users that are fused with a specific cybeast. The cybeast is chosen at random.
Cooldown: 2 or three BATTLES (After all, this is very powerful)