How would {Vigor} and {Sekki, Seasons' Guide} interact with each other? The rulings on Sekki say that all of those happen even if there are no more counters on it, because the wording makes them not dependent on each other, so if the damage is already prevented with vigor I'm not sure if his damage trigger would even happen or can I stack them a certain way to make him produce the tokens and gain the counters from vigor?
Neither is a triggered ability; the use of "As", "when" or "whenever" denote triggered abilities. The use of "if" denotes a replacement effect, which doesn't use the stack.
In that case, the following rule applies.
400.6. If an object would move from one zone to another, determine what event is moving the object. If the object is moving to a public zone, all players look at it to see if it has any abilities that would affect the move. Then any appropriate replacement effects, whether they come from that object or from elsewhere, are applied to that event. If any effects or rules try to do two or more contradictory or mutually exclusive things to a particular object, that object's controller -- or its owner if it has no controller -- chooses which effect to apply, and what that effect does. (Note that multiple instances of the same thing may be mutually exclusive; for example, two simultaneous "destroy" effects.) Then the event moves the object. #
The controller of the object will decide which replacement effect to use.
Replacement effects don't use the stack, and as such don't resolve per se; they just happen.
In this case, unlike stacked abilities where one triggers before the other, the controller of that object chooses which effect to apply.
So after one replacement effect no other can happen? Equals no combo here?
Correct; you can only choose one effect, not both.