Question of start
Also side note, due to the nature of these combatants, being that both have easy insist kills if the other is unaware of the battle we must, for the sake of keeping the thread relevant, assume that both combatants are at least aware of the enemy otherwise the battle is out of a hundred and even split based on a coin toss of who starts the fight and that makes for a boring discussion.
Can we agree to that?
Question of invisibility
We are faced with the invisibility problem. Both combatants seem to have this in one way or another, and in there world a way to be seen. In bleach some people have the ability to see the supernatural. the supernatural do not exist in Elfen Lied (with very vague and mild exception) so it is unknown if she has this or not. In Elfen Lied, as is the case with both kohta's sister and post repair Bondo (manga specifically) some people have the ability to see Lucy's vectors. This assuredly is because hers vibrate at such an intensity that rarely gifted eyes can at least some what see them. As to the abilities of their eyes compared to Ichigo's, well we have no idea.
do to the fact that these can not be tested, we can only make are arguments based on these assumptions.
Lucy can/can't see Ichigo
Ichigo can/can't see vectors.
thought that might be helpful and make up for my bit of a misstep.