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 Monday, 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

Monday

Time	Location	Trainer
Morning 4am-10am	Johto - National Park	School Kid Jack
Teams First Battle School Kid Jack Oddish Voltorb Level 12 Level 14 Second Battle School Kid Jack Gloom Voltorb Level 29 Level 17 Third Battle School Kid Jack Vileplume Electrode Level 38 Level 31 Fourth Battle School Kid Jack Electrode Vileplume Arcanine Level 43 Level 52 Level 52
Morning 4am-10am	Johto - Route 43	PokéManiac Brent
Teams First Battle PokéManiac Brent Nidorina Nidorino Level 20 Level 24 Second Battle PokéManiac Brent Nidorina Nidorino Gyarados Level 32 Level 34 Level 32 Third Battle PokéManiac Brent Gyarados Lickitung Nidorina Nidorino Level 41 Level 38 Level 38 Level 43 Fourth Battle PokéManiac Brent Gyarados Lickitung Nidoqueen Nidoking Level 48 Level 40 Level 58 Level 58
Morning 4am-10am	Kanto - Route 17	Biker Aiden
Teams First Battle Biker Aiden Tentacruel Level 45 Second Battle Biker Aiden Hypno Tentacruel Level 50 Level 49 Third Battle Biker Aiden Hypno Tentacruel Level 55 Level 55 Fourth Battle Biker Aiden Tentacruel Hypno Tentacruel Level 55 Level 58 Level 58
Day 10am-8pm	Johto - Route 30	Youngster Joey
Teams First Battle Youngster Joey Rattata Level 4 Second Battle Youngster Joey Raticate Level 34 Third Battle Youngster Joey Raticate Level 40 Fourth Battle Youngster Joey Raticate Level 54
Day 10am-8pm	Johto - Route 35	Firebreather Walt
Teams First Battle Firebreather Walt Magmar Magmar Level 11 Level 16 Second Battle Firebreather Walt Magmar Magmar Level 25 Level 32 Third Battle Firebreather Walt Magmar Magmar Level 34 Level 37 Fourth Battle Firebreather Walt Magby Magmar Magmortar Level 26 Level 49 Level 58
Night 8pm-5am	Kanto - Route 13	Camper Tanner
Teams First Battle Camper Tanner Sudowoodo Level 38 Second Battle Camper Tanner Sudowoodo Chinchou Level 41 Level 41 Third Battle Camper Tanner Sudowoodo Lanturn Skiploom Level 48 Level 47 Level 44 Fourth Battle Camper Tanner Sudowoodo Jumpluff Lanturn Level 52 Level 52 Level 52