i agree that this question is sort of sophomoric, but that doesn't mean it's not an appropriate question for this site.
i consider it sophomoric (not in a pejorative sense, but in the sense that it sounds like it comes from someone who has a certain level of exposure to philosophy and life) because it takes things in the abstract as if they are removable from specific situations (something that most regulars on this site go out of their way to reject).
another way to say this is that the question posits too broad a definition of coercion. "asserting interests" doesn't have to involve coercion (smooth slip there btw), even when contrary to the interests of others. "asserting" can mean a wide variety of things.
there is also a reification of "involuntary" in the question (i think the wiki def is wrong here too).
but to more or less bypass the first part of the question, and accept enough to directly address the question of what kind of coercion do anarchists accept...
for the nth time, it depends on what kind of anarchist you are.
some anarchists like the rule of meetings, and think that decisions should be made in logical, systematic ways that go through a conscious group process.
others think that different groups of people will have differing ways to decide how people solve problems, and that that diversity is the best we can hope for.
there are probably other models, but that is sufficient for the moment.
and the last part of the question could be another way of getting at different understandings of power. some people define power as a bad thing by definition, some people (post foucault) think of power as something that exists everywhere, and is only bad under certain circumstances (power-over vs power-to-act). in the same way, if you want to define coercion so broadly, then hierarchy and oppression are coercion-used-excessively, or coercion-inherent-in-systems (rather than flexible and relevant to specific contexts).
i think my response here is confusing because i can't decide whether to accept your premises or not. but it was more fun for me that way, so... good luck. :)
edited for typos