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It depends on the latency between the server and the CPC and the payload size.
The server would trigger the enemy attack (as it could host the AI, offloading it from the CPC), and send the message to the CPC regarding the attack. The CPC scans the network system in its game loop which may be multiple frames. It parses the message, calls the appropriate handler for an attack, and then triggers the client-side actions (animation, sounds, messages - these would be in sync for the player at least). The player then would have some reaction time depending on the weapon used, to defend/flee. That defence would then be sent to the network, then onto the server, and the server should add some leeway to cater for latency.
The server wouldn't send each frame's movements though. You only need to say "timestamp1: mob7 casts fireball from x,y in direction dx,dy" for example, and the clients should animate mob7, add the fireball entity, play fireball sound, and then continue to move it independently. The server will check for collisions, and send "timestamp2: fireball hit player3 at x,y" if the server determined it hit the player, or if that player did react in time "timestamp2: player3 raises shield / casts protect / etc" + "timestamp3: fireball fails at x,y".
The client is pretty much only merely maintaining state for each entity (player/creature/door/item/projectile/etc) in the game (that it needs to be aware of), and rendering it appropriately, depending on the state. The server updates the states.
The latency on a 50fps football game however might overwhelm the system. But let's say it didn't - it has to be under 20ms. The game logic runs on the server (which may be a CPC!). The message needs to update player states and ball states and major events (foul, red card, etc), and maybe actions like when the players form a preset formation with an animation to get into that formation. 22 players, 1 ball. Player state is x,y,direction,action - a few bytes. You could probably stream 100 bytes every frame to the CPC and it could handle it (no AI overhead, so some CPU to process and update the states). That's still 5KB/s of data transfer.
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