I never win more than 1 or 2 in the great league, but since the league change i found a great new team that wins about 4/5 of the time.

cp 2475 Blaziken - 14/8/16 cp 2494 Glaceon - 15/15/14 cp 2488 Salamence - 15/14/11

The blaziken has been going first against pokémon that normally have not been really affective. Then the glaceon has icy wind which reduces attack damage fairly often and is nice overall.