For structural bonding and coving (filleting) toughened epoxy is the best choice. It has more flexibility which helps in failure avoidance. It is also more expensive than a laminating resin and you probably won't use enough in 1 or 2 bikes to justify the purchase.

The second best route (read as cheapest and functional) is adding filler to your laminating resin and using that for bonding and coving. It has it's own pitfalls though. If you use microballoons or q-fill, for example, as your thickening agent you will get a brittle, easily breakable bond and fillet. Most manufacturers will have recommendations for their resins.

I have to back up Canaboo on the prep. Prep is everything when working with epoxy. Different materials require different prep. Once again it is usefull to check with your epoxy manufacturer as they will have tested various methods with various materials and will know the best approach for their epoxy.