i was actually putting off answering this question because
I HAVE NO IDEA
but after scrolling through the original pokedex and reminiscing on old favourites i came up with:
Seadra - um, who doesn't love i kick-ass seahorse?
Laprus - because he is pretty and i'm pretty sure i used him for all my water related HMs, although i could be getting confused, i haven't played the original r/b in a long time.
Eevee - please don't hurt me for picking favourites based on them being 'cute', i was pretty young when i first played. I always liked eevee because it was cute, but then of course there's the added bonus that it can turn in to THREE DIFFERENT AND AWESOME DOG SLASH CAT THINGS
i was always terrible at deciding which stone to use to evolve it.
and finally
Drogonite - dratini was cute, dragonair was freaking awesome, its like some kind of dragon snake and then comes DRAGONITE
SO NOW WE CAN FLY
HELLZZ YEAHHHHH