What is the grooms outfit called in Russia?

Answer 1

The traditional Russian groom's outfit is called KOSTYUM-TROYKA, which means a three-piece suit (jacket, trousers and vest/waistcoat). In the Soviet times a troyka suit or just a regular two-piece suit was the most common outfit for a groom.
The colours of the suit tended to be dark for winter weddings, whereas the light colours (usually light grey) were preferred for the summer. The shirt was normally white, and the tie was dark coloured.

The picture on the following web page shows that typical kind of outfit:
http://www.norway.mid.ru/wedding.html

Nowadays, however, the Western traditions are very popular in Russia, so the bridegrooms can be seen wearing dinner-jackets, tuxedos etc (FRAK, SMOKING). The Russian articles on the groom's outfit mention both the traditional and the "new" options:
http://www.tili-testo.ru/articles/style_for_you/92.html
http://svadba.net.ru/publication/publication-11.php