Many people are talking about randori, and most of the time it is about a one way traffic : attack and defense. Of course there are many variations. In Tomiki's way it is totally different, both "players" have the chance to use their techniques. This is the case for "toshu randori". In "tanto randori" there is the situation of attack with tanto and the defense by the unarmed person, but in some cases the tanto man also can use some counters.
Most of the players are referring to the basic kata for their techniques. Only using the "kata form" will result in most of the cases in a not effective technique. We must adapt our kata into a working instrument for randori.
How to adapt our techniques was the topic of a recent seminar in Belgium. You can see an impression at youtube
and for the result of randori training
This randori method is of course a "sports" way of aikido, and from the point of view for a actual fight, it has many mistakes.
But at the end it is great fun and most of the people are always enjoying the "play" of randori.