Every one of my characters have weaknesses, even the characters I rp as.

Shard's main weakness is his gem, it's exposed and can get stolen or shattered. The gem is life force and mind.

Metal has the same weakness as Shard but his gem is more protected, his temper can get the best of him though. He also lacks a firewall to prevent hacking.

Cyber can wear out his powers through emotions, if he's enraged, that fuels his strength. Being calm will have him take more control but steadily and slowly decrease in power, fear will make it slip away fast. He will be weak right afterwards leaving him prone to attacks.

Immortal can't handle hits by those she trusts, this doesn't just use metal weakness, but it physically does more actual damage. Hits in training do not count since she is expecting to be hit by trusted ones. A person she trusts can hurt her far more than a villain's most powerful attack can.

Xiao doesn't have any know weaknesses, but you can hurt her indirectly by hurting close allies for friends.