Sly is always annoying. not only can he go invisible but he can use that level 1 super while invisible. Added in he has a teleport and a counter that are spammabel as hell and all his supers are great just makes he cheap as hell. He needs to be nerfed as well as Kratos too.
When they reach level 1 you should avoid getting sucked into the cluster and jump/evade often.
His level 1 is oped. He can even knock you out if you're behind him when he uses it.