In my opinion if you are after vector art in games I would go for Flash since animation is possible there with certain ease regarding the timeline (unfortunately not free, but there are monthly installments possible - although there is a trial available for testing purposes). For raster animation - Krita Def.
Keeping vector graphics vector in games is generally much too slow - so those will have to be converted to bitmap elements anyway.
Flash is an okay animation tool for character animation: Anime Studio is far more evolved for that type of work (and inexpensive compared for the regular non-pro version). If the game engine supports cut-out animation tools, then either Spriter or Spine offer a superior pipeline and workflow.
Everything really depends on the game graphic style you decide on in the initial game design stage. Only then should you decide on the tool(s) you will use.