Solo, relay, melee, non-cooperative or san da?

There are different scenarios:

1. Solo
   - one person attacks, one defends
   - the attacker aims to be committed and realistic
   - a variety of attacks is necessary
    
2. Relay
   - as above, except attackers take turns  
   - the defender must not be allowed time to return to a neutral state/posture
   - pressure is important
    
3. Melee
   - a group scenario in which nobody takes turns
   - the attacker's need to target weak point and opportunities
   - look out for holes in the defence
   - the defender must not be allowed time to return to a neutral state/posture
   - pressure is important
    
4. Non-cooperative
   - this can be solo, relay or melee
   - the attacker(s) actively seeks to prevent the defender's counters
   - the defender must avoid 'fighting'
    
5. San da
   - this is more akin to a duel or a fight
   - both parties begin in a neutral state and must attack/defend relative to opportunity
   - feinting, luring, deception are crucial
   - the defender must avoid 'fighting'