I play on an iPad mini and would like to know if there are any apps that can handle the skin bases and allow me to submit a custom skin. I have the app Inkist but it crashes when I open the skin bases.

I'm not an iOS user, but you can always check the official sites of the graphics software before downloading in order to check if it will be able to import our bases. If you would like to use a PSD base, you need an app that supports PSD import with layers, transparency, layer blending modes and clipping masks. Inkist can't handle this. Here's what we can read on their site:

PSD Limitations

• Layers are supported, but layer settings (blend modes, transparency settings) are not
• Layers above the bottom three layers will be flattened into the top Inkist layer

Although you can easily use a PNG base or create your own with this software. Inkist supports all the features that you need for creating a skin, including transparency and blending modes. However, I didn't find anytyhing about masks or clipping layers, so if to use our PNG base, you'll need  to make some additional efforts in order to remove those things that are usually handled with masks. It's a painting software, not image processing.