Recent advances in deep learning have significantly improved skin cancer classification, yet persistent issues such as extreme class imbalance and limited intra-class diversity hinder clinical generalization. This study builds upon the Naturalize framework by proposing a robust augmentation pipeline targeting rare lesion types in the ISIC 2019 dataset. Leveraging SAM-based segmentation and StyleGAN2-ADA synthesis, we construct two fully balanced datasets with $text2, 4 0 0$ and $text7, 2 0 0$ images per class. The method enhances representation of underrepresented classes (DF, VASC, SCC) while preserving contextual realism through background blending and geometric transformations. Across eight pre-trained CNN and ViT models, Xception trained on the 7.2 k dataset achieved the best generalization with 66% test accuracy and macro F1-score of $text0. 6 4$. Despite challenges in synthetic fidelity (e.g., FID scores of 62 for VASC, 58 for DF), the proposed pipeline marks a significant step toward equitable, high-performing AI diagnostics. Our framework offers a reproducible, end-to-end strategy for scalable skin lesion classification under real-world data constraints.