Looking on the internet deeply has found these results:

is remained is the most popular phrase on the web.

is remains 131,500 results on the web	is remained 1206,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Jun 29, 2015 ... News / Middle East. With 'Caliphate' One Year Old, IS Remains Strong. Print; Comment (6); Share: FILE Iraqi troops advance in Ramadi, pockets of IS remains. Associated Press. 4:32 PM, Dec 28, 2015. 4:33 PM, Dec 28, 2015. iraq \| isil \| isis \| islamic state \| ramadi�... Iraqi troops advance in Ramadi, pockets of IS remains. Associated Press. 3:32 PM, Dec 28, 2015. 3:33 PM, Dec 28, 2015�... On occasion, historical human remains (that is, remains that were interred a long time ago) are accidentally discovered in Delaware. These discoveries are often�... Image taken a from video shows a�...	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

is remains

131,500 results on the web

is remained

1206,000 results on the web

More popular!

Jun 29, 2015 ... News / Middle East. With 'Caliphate' One Year Old, IS Remains Strong. Print; Comment (6); Share: FILE
Iraqi troops advance in Ramadi, pockets of IS remains. Associated Press. 4:32 PM, Dec 28, 2015. 4:33 PM, Dec 28, 2015. iraq | isil | isis | islamic state | ramadi�...
Iraqi troops advance in Ramadi, pockets of IS remains. Associated Press. 3:32 PM, Dec 28, 2015. 3:33 PM, Dec 28, 2015�...
On occasion, historical human remains (that is, remains that were interred a long time ago) are accidentally discovered in Delaware. These discoveries are often�...
Image taken a from video shows a�...

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.