Plugins
Where can I use my languages that I have created?1
The main platform is MPS itself, or a custom IDE based on MPS (so called RCP).
Are MPS language often used as plugins in Intellij IDEs instead of MPS itself? (an IntelliJ IDEA plugin, not custom RCP)
No, this functionality is not used very often.
How can I find plugins on the JetBrains Marketplace that are usable in MPS?
Searching for the word MPS in all categories should do the trick.
Why do many IntelliJ plugins don't work with MPS?
Many of these plugins are working in combination with the text editor. MPS uses custom editors. It doesn't use documents and the Program Structure Interface(PSI) because MPS models are not text based. Using plugins that are not developed for MPS can interfere with certain features of MPS (e.g. find usages isn't working anymore).
My plugin is incompatible with the current RCP version.
Specific Languages Blog — Fixing the 'Plugin incompatible with the current [CUSTOM RCP] version' error
Are there any general purpose plugins for MPS from the community?
Have a look at the plugin section of mps.rocks.
Which kinds of plugins are there?
Specific Languages Blog — Two kinds of MPS plugins