Newfy "English" is the Quebecois of English dialects. It's barely understandable by the rest of the country. An Englishman and an american/Canadian will be able to understand one another mostly with no problem. There will be the odd slang word that trips 'em up but, overall, the message comes across. Newfy is hard to understand what most words are, the accent is thick.

Similar to a Scottish or Welsh accent, I should think, to north Americans.

American English is the most spoken kind and pretty close to British RP, so it's not Quebecois. If you want a weird dialect, maybe Jamaican patois, or some of the ones from backcountry UK.

Probably Finland Swedish, a group of Swedish dialects spoken in parts of Finland.

Somerset countryside, they're unintelligible.

Well, I believe Quebecois has a reputation for being "more French than French". For example, they refuse to say "le parking" like they do in France. Quebecois insists on using "le stationnement".

Maybe that's what they meant about Norst and Norwegian?

In the UK, Scots is close enough to English to be almost comprehensible to an otherwise unprepared British English speaker. (Case in point: Trainspotting.)

For German, I guess Pennsylvania Dutch would come closest? At least in the sense that it's a variety of German spoken in North America. It's barely understandable for modern-day Germans.

Cypriot Greek

I’d guess Cajun English? Since it has so much French influence and also is its own distinct dialect with unique origins.

I think most larger (or older) immigrant communities have their own dialect. Runglish is Russian spoken with lots of words borrowed-adapted from US English.

In parts of Eastern Ukraine and Western Russia, there is also surzhyk, which is a difficult-to-describe blend of both languages, often difficult to comprehend to those who do not speak both or dis not grew up in the area.

@may_be Quebecois is only derived from French
I am Quebecois, and despite my slang, nothing is really derived from English.

Plus québécois que moi, vous allez mourir 😉
Faque, rien de pareil dans mon parlé très original face au Norvégien ou l'anglais États-unien.. 😋

Svenska är inte mitt språk, men svaret är självklart skånska.

Not sure if this answers your question exactly, but I once heard a guy say "I speak English and bad English."

For me, I speak the King's English (aka English from England), and I also speak American English. I prefer the King's English, but there are times when American English is just better. I could not tell you how to spell manoeuvre and even typing it, I have to Google it to be sure it's right because fuck that word sideways. Maneuver just looks better. But honour, valour, even colour are just... better... than their American counterparts. And centre and metre just feel right, though it's pronounced -ter. As for theatre, theater and theatre are two different things. Theater is the same thing as cinema, and theatre is where a stage play is performed, or like, the theatre of war. It's a more dramatic term.

Ukrainian and Russian has a similar relationship, only with Polish in place of English.