Here are my 6 Pokemon on my very first playthrough of Pokemon Heart Gold:

Feraligatr

Ursaring

Ampharos

Crobat

Golem

Gyarados (that Shiny one but I won't count it as my first shiny since anyone can catch it)

And those were my 6 Pokemon from my very first playthrough of Pokemon Heart Gold. If you remember what Pokemon you had on your first playthrough, comment down below what they are.