In Verdanturf town there are a few things that you should probably do:
The second house from the left on the bottom right is Wally's house, if you visit him, his aunt and his uncle, you can learn that their daughter is in the tunnel because her boyfriend is the man you found on the opposite side of the tunnel who said he was digging by himself.
In Emerald after you visit Wally he will call you and register you on match call.
Check out this side of Pokémon Ruby and Sapphire/Rusturf Tunnel, sadly you cant bring the two lovers together until after you beat the 3rd Gym(Gym Leader Watson).
If you talk to the lady in the house first from the left you'll be able to get the mood rated for your lead Pokémon.
In Ruby and Sapphire there will be a contest hall where you can first enter in contests
In Emerald you are not able to join contests until you reach Pokémon Ruby and Sapphire/Lilycove City, instead you get the battle tents, which are fairly fun if you know your type match-ups and you have a little bit of luck.
Items
TM45 (Attract) - from a woman inside the Contest Hall (R/S)/Battle Tent (E)
Contest Past (R/S only) - from the Contest Hall receptionist
Nest Ball (Emerald only) - reward for clearing the Battle Tent
