[wlk]

When required people just omit the diacritic signs and replace the letter with regular ASCII letter, so for example: ż->z, ł-l, ó->o, etc.

When used in (computer) writing this is very readable, but no one would do this with handwriting, I think most common cases nowadays would be SMS messages (especially on dump phones) or some weird displays that are unable to properly render diacritic letters.