To make a Batman skin in Planet Minecraft's skin editor, follow these steps:

1. Open Planet Minecraft's skin editor.
2. Select the base skin template or create a new one.
3. Choose the color palette and tools.
4. Select the dark grey color for the suit and the black color for the mask.
5. Use the paintbrush tool to draw the suit, starting from the torso and arms, then the legs.
6. Use the eraser tool to create the symbol on the chest in black.
7. Use the same brush tool to draw the mask with black color.
8. Use the spray paint tool with yellow color to create the belt and draw the details.
9. Use the same spray paint tool with white color to create the eyes and highlight the symbol.
10. Use the shading tool with darker tones of grey to add depth and definition to the suit.
11. Save the skin and upload it to Planet Minecraft.