you talk to a guy near the rest house before the rusturf tunnel entrance.
You can find it Rustro mart, Rusturf tunnel, trick house (in some marts. I think in the elite four pokemon center) Rustboro Mart, Rusturf Tunnel, Trick House
The Timer Ball can be purchased in Rustboro City after going through Rusturf Tunnel from Verdanturf Town for the first time, or from Two Island Market Stall after saving Lostelle, beating the Elite Four, buying every item in the stall at least once and then leaving and returning to the area.
Make sure that you have delivered the letter you got from the Devon Corp. Director (Mr. Stone) to Steven, and safely returned the Devon Goods to Captain Stern in Slateport city. Use Rock Smash to get rid of the remaining boulders in the Rusturf tunnel. Go back to Rustboro through the Rusturf tunnel and outside there is that guy you saved from getting robbed of the Devon goods. he will give you a repeat ball, and the Rustboro Market will now be selling timer balls and repeat balls.
Go to vendaturf town and go through rusturf tunnel. When you do you will see the man from Devon corp and he will say they developed a new type of pokeball and give you a repeat ball. Then go to the rustboro city and go to poke mart and they will have repeat and timer balls for sale, i hope i helped.
After you beat Mossdeep City gym, go to Rustboro City, then go east to Rusturf Tunnel, and there should be a guy in green just outside who looks like he's from Devon Corp. Talk to him, and he will give you a repeat ball. Now return back to Rustboro City and enter the pokemart. Now you have unlocked both Timer and Repeat balls. Both cost $1000 each. Timer balls are great to catch legendaries including relicanth and are more likely to succeed with each turn!
The timer ball in Pokémon Sapphire is located in Rustboro City. You must go to Mauville and talk to a guy located in front of the tunnel, he will tell you this.
No they are detonated by sensing the sound and movement above them.
Go to Diamond Mines if you aren't already there. Go to the way right and the timer thing is there. You need a hard hat to go there though. Move quickly after you turn off the electricity.
Look through the options page/menu whatever its called and just look through it
Connection establishment timer, persist timer, keepalive timer, retransmission timer
I have found out it is impossible to open it when you already started it. So you just have to wait for the timer to go off.
I don't know if this is the answer you want but if they already have a partner the co-worker is a 2 timer