There's an issue with Android Emulator Plugin 3.0 not working with current "Command line tools only" sdk package ( https://developer.android.com/studio#downloads). I used it on my build server, which obviously is something to choose for a build server (in comparison to full Android Studio package)

The issue seems to be located in AndroidSdk.java:161

Plugin tries to use old {$ANDROID_SDK}/tools/emulator path to run the emulator instead of {$ANDROID_SDK}/emulator/emulator. 

[android] Erasing existing emulator data...
$ /var/lib/android/tools/emulator -ports 5724,5725 -report-console tcp:5825,max=60 -avd pixel-2-api28 -wipe-data -no-window
FATAL: Cannot run program "/var/lib/android/tools/emulator": error=2, No such file or directory
java.io.IOException: error=2, No such file or directory

The issue is about how the plugin checks tools versioning, it looks for a property named Pkg.Revision in file {$ANDROID_SDK}/tools/source.properties.

For "Command line tools" it looks like this:

Pkg.Revision=1.0
Pkg.Path=cmdline-tools;1.0
Pkg.Desc=Android SDK Command-line Tools

For earlier SDKs it looks like e.g this: 

Pkg.UserSrc=false
Pkg.Revision=26.1.1
Platform.MinPlatformToolsRev=20
Pkg.Dependencies=emulator
Pkg.Path=tools
Pkg.Desc=Android SDK Tools

The plugin checks if version is higher than 25.3, which for this command line tools package is obviously not.