The entire periodic table. He can anything into anything. Iceman would be a sitting duck to him. Turn him into oxygen. Or iron. Or krypton. Or neon.
He's not. He finds it difficult to shape alien elements. But he has. Once he trapped Superman in kryptonite bubble and blasted him with red sunlight. His powers doesn't work on magic. Like WW's lasso. He tried and failed miserably on that one.