Cyndaquil7! Omg ... I haven't seen you around here for ages and ages and ages! You haven't replied for so long? Are you still reading this? I hope you are, you were like one of my most dedicated readers.

But sure, here's a list. I'm bored anyway.

Lisa:

Aipom (obtained before Chapter 1)
Fiskmire (evolved from Quagsire in Chapter 24, who evolved from Wooper in Chapter 7)
Dratini (caught in Chapter 10)
Elekid (given to Lisa by Jack the Sailor in Chapter 12)
Vulpix (caught in chapter 14)

Gavin:

Natu (obtained before Chapter 5)
Staryu (caught between chapters 7 and 8)
Girafury (evolved from Girafarig in Chapter 29; Girafarig obtained from Lisa in Chapter 8)
Green Lanturn (caught in Chapter 10)
Ditto (caught in Chapter 18)

Marina:

Starmie (obtained before Chapter 17)
Golduck (obtained before Chapter 17)
Tentacraw (obtained before Chapter 17)
Mudkip (obtained before Chapter 30)
Bayleef (obtained before Chapter 40)

Wesley:

Omanyte (given to him by his parents in Chapter 39)

Jean:

Bulbasaur (given to her by her parents in Chapter 39)

Kris:

Wigglytuff (evolved from Jigglypuff before Chapter 38)
Butterfree (given to her from Lisa in Chapter 20-21)
Ledian (evolved from Ledyba before Chapter 38)
Misdreavus (obtained before Chapter 2)
Feraligator (evolved from Croconaw before Chapter 38)
Growlithe (caught in Chapter 20)

Hiro:

Typhlosion (evolved from Quilava before Chapter 35)
Venomoth (evolved from Venonat in Chapter 4)
Dewgong (evolved from Seel before chapter 35)
Heracross (caught in Chapter 3)
Weedle (caught before Chapter 2)
Furret (caught before Chapter 35)
Magneton (caught before chapter 35)

Darius:

Dragonair (given to him by Lance, his father, before chapter 35)
Dratini
Gyarados

Anna:

Psyduck (caught before chapter 2)
Scizor (caught before chapter 14)

Tom:

Gastly
Haunter
Haunter

Miki:

Umbreon
Blissey

And, frankly, that's everyone I can think of who is a major recurring character. I think so, anyway. I did Anna because she was kind of important before.

Hope you find the list helpful Cyndaquil!

Cheers!