Does that mean when Cloud uses omni slash he shouts "Omni slash" and Sephiroth shout "anti omni-slash" and counter the move. Then Cloud uses "anti-anti omni slash" and vice versa until someone with the most "anti" win since this show his technique overcome the others.

So bascially, one will use his technique and the other will wait there and observe how to counter his technique? This is a prove of skill?

Anyway, Loz did uses some special technique in the movie and Cloud uses blade beam to counter it.

So must Loz keep hitting the ground or uses some other fancy techniques and Cloud just keep using limit break to counter it until one give up?

Also, a limit break is a technique that you are talking about

Let's just say in a real fight, will you wait for your opponent to use his special kung fu technique and you counter it with one of yours special kung fu technique too. Then you wait for him to uses his other techniques or vice versa.
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If you want some logic like how Cloud can uses Omni Slash and we can't, well, this movie is called "Final Fantasy VII Advent Children" done by people using creativity.