1. Check What has Already been Fixed
Pixelmon developers are constantly fixing bugs. They probably have a million of them.
So before making a bug report, check the changelog on the Wiki to make sure it has not already been fixed.
Furthermore check to see if a report exists already, as it will be fixed in a future version of Pixelmon.
2. Check Previous Reports
Cannot stress this one enough. Check the previous reports. It is very tedious but overall it will allow the developers to make solid gameplay without being bogged down with a million bugs.
If it already exists, the best thing you can do is provide more information.
3. When you make a bug report, make it detailed.
In addition to a detailed report include the following information:
Minecraft version
Beta version
Forge version
Crash logs
4. Be patient.
Bug fixes take time!
5. One bug per report
Only submit one bug per report. Developers do not like big lists of bugs, and you’re more likely to be ignored.
This also allows for proper bug tracking and developments.
I know, I know, lots of rules. But, this will truly help make Pixelmon better.