Mandarins that wont eat frozen really are a pain unless you have a large enough tank or a refugium with macro. If you really want a mandarin but dont have space for a big tank you could have a smaller tank filled with macro that the mandarin lives in. I have a 20 with a caleurpa forest that supports a mandarin. Although he also eats some frozen. Problem is he hides a lot. The tank is basically just rock, a couple of caleurpa species, the mandarin, a goby and some urchins. I also had a larger tank with a pair of mandarins and a caleurpa forest.
Culturing pods alone is kind of a pain, but it can be done. I think the sellers of the tigger pods has info on it on their site. I dont think its worth the effort and I never had luck culturing the tiggers. Its much easier to get amphipods and copepods from someones tank via chaeto and start a refugium.
Scooters are MUCH easier than mandarins to get to eat frozen and flake foods. So that would probably be the way to go. The key is to find a nice fat one. THey shouldnt look bony in any way, but they almost always do. Look at the belly AND the back, the back should have meat on it, it shouldnt look like a bony plate. Most that you see in the stores are really skinny. The skinny ones dont always make it, Ive lost a few even in copepod filled tanks. I learned my lesson about ordering dragonets online, dont do it. But heres what Ive done and has worked with some really skinny scooters and mandarins. When I first get them I put them in their own SMALL tank with a ball of pod filled chaeto and rock. I feed black worms one day and freshly hatched brine the next. I alternate until they start putting on weight. Then I start feeding frozen mysis and frozen brine on alternating dates with no other food options besides the pods in the tank. I will not add the fish to the larger tank until it is fat and eating frozen on a regular basis. They should have a big rounded belly and you should be able to see that they have some meat along the dorsal spine.
Good luck