Eg. For Mono-Poison, Does it Count if I use Crobat or Drapion etc.?
OR Do I have to Use only Poison like Seviper and Garbordar ?!
Same goes for all the Challenge Medals because For Flying it's gonna be Crazy and Kinda for Dragon but 6 Haxorus FTW XD
No, you can have Pokemon with secondary typing that is not poison (or whatever type your team is) in a Monotype team. (e.g. Toxicroak, Crobat, etc.)