Serbo-Croat-Bosnian(SCB),[10]Bosnian-Croatian-Serbian(BCS),[11]andBosnian-Croatian-Montenegrin-Serbian(BCMS)[12]– is aSouth Slavic languageand the primary language ofSerbia,Croatia,Bosnia and Herzegovina, andMontenegro.
It is apluricentric languagewith four[13]mutually intelligiblestandard varieties, namelySerbian,Croatian,Bosnian, andMontenegrin.
https://en.m.wikipedia.org/wiki/Serbo-Croatian
Czech and Slovak languages are two closely related and partiallymutually intelligibleWest Slavic languages;
https://en.m.wikipedia.org/wiki/Czechoslovak_language
Slovak is closely related toCzech, to the point ofmutual intelligibilityto a very high degree,[8]as well asPolish.
https://en.m.wikipedia.org/wiki/Slovak_language
De asemenea rusa formeaza un continuum lingvistic cu ucraineana, belarusa si poloneza.
Russian is partially mutually intelligible with Ukrainian, Rusyn and Belarusian.
Russian has 85% intelligibility with Rusyn (which has a small number of speakers in Central and Eastern Europe). Russian is also 85% mutually intelligible with Belarusian and Ukrainian in writing. However, Russian is only 74% mutually intelligible with spoken Belarusian and 50% mutually intelligible with spoken Ukrainian.
https://www.fluentu.com/blog/mutually-intelligible-languages/
Can Poles understand Slovaks?
Czechs and Slovaks generally can communicate with a few rough spots from what I see; Slovak is aparently the bridge (most) language of the family asPoles claim to understand Slovaks very well but not Czechs. Most basic vocabulary and certainly basic verbs are very similar.
https://bishop.aussievitamin.com/are-polish-and-slovak-mutually-intelligible
Dialectul moldovenesc si dialectul ardelenesc sunt slab mutual inteligibile cu limba romana literara, probabil pe undeva pe la 25-50%.