Well no one comes to think about T.A.C and O^2 being female but I MAY have proof that they are girls.

Clues for T.A.C

1) the way hal designed T.A.C very well reminds me of rouge the bat.

2) the way that T.A.C walks (or runs) is a elegant tip-toe

3) when you see the "spring breeze" opening theme, all the T.A.Cs are all wearing a pink uniform

4) T.A.C's jump is a elegant girl-ish type jump

Clues for O^2

1) O^2 wares a halo over her/his head

2) if you look at the art section of KRR in KDL3, O^2 looks like she/he has female eye-brows

3) the kirby64 O^2 design looks a LOT more female then in KDL3

4) she/he looks like she/he has a laid-back prissy-type attitude

well that's all for now folks!