He stood up for the farmers, who didn't want to sell their land to the property developers. [He took the farmers' side.]
He stood up to the property developers, who wanted to buy the farmers' land.
[He resisted the property developers.]
As for other meanings, I can only think of the obvious physical one:
He's a real gentlemen - he always stands up for ladies on the bus.
(He's not championing their cause; he's just offering them his seat.)
- For Teachers