I have a hard time imagining Rainbow Dash with (big?) boobs because, err, she's athletic. If you're comfortable or really want to add feminine curves then go for it although I personally wouldn't mind at all seeing a Dash with a "male body" because she is kinda tomboy-ish anyway.
Masamune Date - Sengoku Basara
Team Aqua Grunt (male) - Pokémon Ruby/Sapphire Version
*~Next con I'm attending~*
FIN Tracon (13-14th September 2014)
SAT Hajime Saitō - Hakuōki: Shinsengumi Kitan
SUN Ryūnosuke Ibuki - Hakuōki: Shinsengumi Kitan