In previous games, to get rematches with trainers, you used the VS Seeker to see if the trainers were willing to battle. In HeartGold & SoulSilver however, the rematches are done a different way. Firstly, only a few dozen trainers in Kanto & Johto are capable of being battled again.

In order to get the rematch, you have to receive the PokéGear number from the trainer in question. Then, on a certain day, you will need to ring the trainer in question to organise a rematch. It is not guaranteed that a rematch will be discussed when you call but keep trying and you should get it. Below is a list of all the trainers, battleable on Friday, and their teams including their first team and each team's increase in level. Click the other days to go to their page

Monday | Tuesday | Wednesday | Thursday | Friday | Saturday | Sunday

Friday

Time Location Trainer
Morning
4am-10am
Johto - Route 38 School Kid Chad
Teams

First Battle
School Kid Chad Mr. Mime
Level 20
Second Battle
School Kid Chad Mr. Mime Magnemite
Level 29 Level 30
Third Battle
School Kid Chad Mr. Mime Magneton
Level 39 Level 38
Fourth Battle
School Kid Chad Mr. Mime Magneton
Level 46 Level 56
Morning
4am-10am
Kanto - Route 2 Bug Catcher Rob
Teams

First Battle
Bug Catcher Rob Beedrill Butterfree
Level 40 Level 39
Second Battle
Bug Catcher Rob Beedrill Butterfree
Level 45 Level 42
Third Battle
Bug Catcher Rob Beedrill Butterfree
Level 52 Level 48
Fourth Battle
Bug Catcher Rob Beedrill Butterfree
Level 56 Level 56
Day
10am-8pm
Johto - Route 45 Hiker Parry
Teams

First Battle
Hiker Parry Onix
Level 30
Second Battle
Hiker Parry Onix Graveler
Level 38 Level 35
Third Battle
Hiker Parry Steelix Graveler
Level 41 Level 37
Fourth Battle
Hiker Parry Steelix Golem
Level 56 Level 52
Day
10am-8pm
Kanto - Route 13 Young Couple Tim & Sue
Teams

First Battle
Young Couple Tim & Sue Kadabra Psyduck
Level 41 Level 46
Second Battle
Young Couple Tim & Sue Kadabra Golduck
Level 45 Level 50
Third Battle
Young Couple Tim & Sue Kadabra Golduck
Level 48 Level 52
Fourth Battle
Young Couple Tim & Sue Alakazam Golduck
Level 54 Level 56
Day
10am-8pm
Kanto - Route 26 Ace Trainer Jamie
Teams

First Battle
Ace Trainer Jamie Rapidash Flaaffy
Level 36 Level 31
Second Battle
Ace Trainer Jamie Rapidash Ampharos
Level 38 Level 37
Third Battle
Ace Trainer Jamie Rapidash Ampharos
Level 42 Level 40
Fourth Battle
Ace Trainer Jamie Rapidash Ampharos
Level 56 Level 59
Night
8pm-5am
Johto - Route 33 Hiker Anthony
Teams

First Battle
Hiker Anthony Geodude Machop
Level 11 Level 11
Second Battle
Hiker Anthony Graveler Machoke
Level 33 Level 32
Third Battle
Hiker Anthony Graveler Graveler Machoke
Level 37 Level 38 Level 40
Fourth Battle
Hiker Anthony Graveler Golem Machamp
Level 41 Level 49 Level 55
Night
8pm-5am
Kanto - Route 15 School Kid Billy
Teams

First Battle
School Kid Billy Parasect Poliwhirl Ditto
Level 39 Level 37 Level 35
Second Battle
School Kid Billy Parasect Poliwhirl Ditto
Level 42 Level 43 Level 40
Third Battle
School Kid Billy Parasect Poliwhirl Ditto
Level 46 Level 47 Level 46
Fourth Battle
School Kid Billy Mr. Mime Parasect Poliwrath Ditto
Level 50 Level 55 Level 53 Level 51