I'm using extra fine (0.5 mm) G2s from Pilot. I'm a big fan, and I just got this pack, from which I think I can get most of the colors to represent each MLB team. I had blue, green, red, and black up until receiving them.
The outlier was brown for the Padres: I think Pilot offers brown ink pens, but not for the G2 0.5, so I ordered this from Pentel specifically for them.
Nice!!!
Looks like you could use this, then: