Girl Partner. Huhuhuhuhu
When selecting a match partner, characters with histories (good or bad) will have something to say on the character select menu when you select the portrait but before you you confirm superstar status and color. Use the pre-match tag screens (exhibition is best) to determine the viability of the coupling. Wrestlers shaking their heads are a bad sign.
If you're in need of real help, select any two characters and enter an exhibition Tag Match (or any regular Tag Match, although these are not always available). On the VS screen, there is an icon corresponding to each pairing. The halo around the icon signifies a good match-up, whereas a lightning bolt signifies a bad match-up ('sparks' between the two). Neutral match-ups have no outstanding symbol.