No problem!
I'm glad you appreciate them. As far as my ideas, here's what I'm thinking as far as "winposes":
Leo: A serious man - er, turtle - of honor, there's really only two things that Leonardo would do after defeating an opponent: either make some dramatic, serious pose (Perhaps sheathing his weapon, standing with legs apart, and gazing at his fallen foe), or bow respectfully (As any honorable martial artist would after defeating a worthy opponent).
Don: I'd say that Donatello would likely give his bo a little spin, then strike a pose in which he faces the viewer, open palm thrust toward the viewer, his other hand holding the bo at a downward angle.
Raph: Being a bit showoff-y, Raphael would likely show off a few kicks and/or punches as if to say, "Oh yeah... I whooped your shell and I've STILL got energy to fight!"
Mikey: Let's face it... Michelangelo has but one word appropriate enough to describe a truly awesome win... All together now, folks:
"COWABUNGA!!!" (Feel free to use the sprites used at the end of a Turtles in Time level for this one)