OK here's a few pointers! This is all I can think of right now but I'll add more later if I remember anything.
Turning answers into comments
If someone replies to another answer (or to a comment) by posting an answer, it should be made a comment. For example people saying "thanks".
Just click "edit" on the answer and there is a checkbox to convert to a comment. Choose the right post from the drop down - it's normally auto selected but you may want to move the comment to under the question instead of answer.
Questions should have decent titles so you know what it's about before clicking on it. For example "EV question" isn't good because it's not clear, but "Does the Macho Brace increase EVs?" would be better.
If a question is really badly written then it should be cleaned up if possible. Often we get people typing things like:
my team is charizard iron tail earthquake flamethrower magikarp splash flail hyper beam
It should be more like:
My team is:
Charizard - Iron Tail, Earthquake, Flamethrower
Magikarp - Slash, Flail, Hyper Beam
Doesn't need to be fancy with bullet points or anything, just a few line breaks and commas makes a big difference. Rewriting stuff into perfect sentences would take forever on here ;)
And tags can be edited too. If someone asks about a specific game or Pokemon, it should have that as a tag, e.g.
This is less common (apart from converting to comments as above). If there is an answer that has good content but is badly written, has lots of spelling mistakes, or is one long run-on sentence, you can edit it to add formatting.
Normally it's not worth the hassle to edit answers because someone else wrote a better answer. So just vote that one up :)