Hmm that's interesting. I would hesitate on Kayle as I rarely recommend gold-intensive champions to lower elos. Kayle can be insanely strong and can solo-carry but getting to that point I would say requires good cs-ing and the ability to lane well. Kayle bullies a lot of melees, but managing mana and auto-spacing can be difficult for new players. I personally find Kayle deceptively challenging to play properly.
Ahri is also a bit weird for me. I think she is a well-rounded champ, but I don't know how well I see her handling in an average bronze game. Charm can be a hard skillshot to land, and you also have to be able to use her ult aggressively without killing yourself, which for me is a higher level of decision making.
That being said if the original poster was willing to put in the practice on these champs either would definitely be effective in bronze and silver. I just tried to pick champs that do a lot of damage, capitalize on the poor-positioning of bronze, and/or have strong point-and-click CC.