I have not had great success training a new fish to pellets. What has worked for me is competition with other fish. One alone will taste a pellet and spit it out, but one that sees another go for a pellet will usually eat it.
I haven't had trouble training longear to pellets. They seem to eat anything.
But competition has helped with others. My largemouth bass was trained that way. Would not eat pellets at first, but after watching the other fish for awhile he finally joined in.
Juvenile shadow bass were the same way. At first they had no interest in prepared foods, but after watching green sunfish and others they finally started taking them.
I wonder if making the pellets move around a lot would trigger feeding. With our sculpin we'd blow them across the bottom with a powerhead so they appeared to be evading him, and finally he started taking them. In fact after he started eating pellets he had very little interest in live foods, due to having to put in more effort to catch them.