I love making cake pops - see my link below.
I have made many biscuit and cream cheese varieties, oreo, white tim tam, dark tim tam, mint slice, Woolworths has their own brand of Select Raspberry & Cream which is delectable, just like a strawberry cheesecake when added with the cream cheese! and over the weekend just did some butternut snap one's...they are delish too!
I have tried cake boxes, just a simple buttercake, vanilla, and red velvet but found them too sweet. I might embark on a choc mud with choc ganache next time instead of buttercream or icing to bond with! Therefore I think your choc fudge should work - the texture needs to get to a playdough consistency, and with which needs to be dense, so don't think sponge would work, as it may be too light and may break when sticking stick into it, even though it may be chilled from fridge...
The american candy melts dont work on their own like **Leprechaun** said as they need to be thinned down, in the US they use paramount crystals - here we use copha. I have used Candy melts with our copha but again found the melts too sweet. As I believe we here are used to our nestle and cadburys choc.... so I use either powder or gel paste (with flo coat)...
hope this helps