YOGAS
Su: Can you tell me how many ways a deb. planet gets neechabhanga?
POINT 1:
Which are the neechabhanga planets:a) planet which lords the exaltation rasi of that graha

ex. for Sun it would be Mars (Aries is exaltation sign)

b) planet which lords the debilitation rasi of that graha

ex. for Sun it would be Venus (Libra is debilitation sign)

c) planet which gets exalted in sign of debilitation

ex. Sani has exaltaion in Libra which is sign of debilitation of Surya.

Conclusion: Mars, Venus, Sani are the neechabhanga grahas for Surya.

POINT 2:
Three ways of neechabhanga:

i) by grace of God - uccha avastha in Dharma-amsa. After initial setbacks native gets phala.
ii) by society or mantra - when neechabhanga planets are in kendra to Moon.
iii) by own skills/supports - when neechabhanga planets are in kendra to Lagna.

So when:

i) Surya is in Mesha-amsa (Purna Neechabhanga 100%)
or
ii) When Mars, Venus or Sani are in Kendra to Moon or Lagna (75% Neechabhanga)

Surya achieve Neechabhanga state