Is it permissible to seek help directly from Hazrat Ali or other Masoom figures instead of Allah using their Waseela? If yes, what evidence exists in Sunni and Shia Islamic texts?
The fact that everything is in the hands of Allah (SWT) is unchangeable and non negotiable whether you ask directly from Allah or request help from Allah's humble servants to get your work done. When you ask help from Allah's humble servants, you are not asking them to get your work done by them with out Allah. You are seeking their help because of their status with Allah. Wahabi claim based in their misunderstanding the real Tawheed, but Quranic Tawheed states that seeking help from Allah;s humble servants is just like seeking from Allah. We read in Sura Al-A'raaf , verse 134: And when the punishment fell on them they said: O Musa (Moses) : Invoke your Lord for us because of His Promise to you, If you remove the punishment from us, we will believe in you and let Israel's children go with you.
When they told Musa ( If you remove the punishment from us) he never object on them, because he knows that Allah and only Allah removes the punishment and they asked Prophet Musa to do that because of his status as a humble servant of Allah.
We are allowed to seek directly from Allah or seek from His humble servants whose supplication to Allah in our favor is more effective that our supplication,v knowing that everything is in the Hands of Allah.
Wassalam.