Torbay-born Moore, 22, has joined on a 28-day loan while McCoulsky, 19, will be at Plainmoor until mid-January.
Manager Kevin Nicholson hopes the strikers will arrest Torquay's poor form, which has seen the side not win for seven matches in all competitions.
"The boys that are here already need to see this as a challenge now," Nicholson told BBC Sport.
"They've had my backing the whole time I've been here and I will do everything in my power to help them improve as people and players and help us get the results we should be getting."
Moore, who has spent time at Yeovil Town, has scored six goals for the National League leaders since joining from Norwegian Premier League side Viking FK in January.
Highly-rated youngster McCoulsky made his Bristol City debut in their EFL Cup defeat by Hull City in October.
"Kieffer's proven at this level and higher, he's a very hard-working guy and the chance for him to come here, play some football and push some of our lads was something that he wanted to do," added Nicholson.
"Shawn is a young boy with bags of pace and bags of energy, he's been knocking on their first-team door for a little while."
Torquay United have signed Forest Green striker Kieffer Moore and Bristol City forward Shawn McCoulsky on loan.