I would probably say "Difficulties to overcome", but it would depend on the complete phrase!

Difficulty or difficulties is usually followed by just the gerund, or 'with' + gerund. So you would say: I have difficulty understanding He has difficulty walking That's the grammar, but I'm not sure about the meaning of your phrase. It's not clear what 'difficulties scaling' would mean. Scaling what? Or do you mean 'difficulties climbing'? If you can provide more context, perhaps we can get a better translation.