I agree with David on this. It'd be TOO big and huge, and while it might be cool to have multiple enemy aliens all the canon ones would just be too much. In the Pandorica opens, the only reason they all got together was because they thought the Doctor, their common enemy, was going to destroy the universe. What other reason would they have to get together?
Daleks still want to exterminate EVERYTHING. Sontarans would still want the glory of defeating the Doctor BY THEMSELVES. Most Raxacoricofallapatorians are good, just the Slitheen family was doing something bad. The Silurians aren't bad, either, just one of them wanted to get rid of the humans in order to reclaim the planet instead of making a compromise. The Ood are friends of the Doctor, just they were being controlled by that devil-thing in that one episode.
It was a good idea; new ideas are always encouraged. Though I'm not sure how'd it ever work. Sorry.
The risk I took was calculated, but man am I bad at math