having a bit of nostalgia, playing a new game on pokemon blue - how's this for a loadout?

Currently at Cerulean City

Abra - Lvl 13 (haven't raised it before)
Bellsprout - Lvl 15 (Unique to Blue)
Wartortle - Lvl 23 (Because Blue)
Sandslash - Lvl 22 (Unique to Blue)

Am going to get:
Voltorb - haven't raised it before

Still haven't decided on my last one. What would you recommend? Playing on my Game Boy Colour, so no time machine trading