You can make any team have full stats by editing each players stats and upgrading them to 99. However, be warned; if you start with this team in manager mode, your salary will be high. Make sure to cut their contracts down as soon as
possible.

To start with a five star team immediately in career mode, go to the team management screen. Put the bad players in the first eleven so that your team will be a four star team. Then go to career mode. Your team should be there. Save your career, then go back to the team management screen. Put the first eleven players back, save it, and you will have the normal team on friendlies and your team on career mode.