If you haven't taken at least psych stats or an equivalent or research design/ experimental psych you may have a hard time getting into phd programs as these courses are prerequisites for almost all programs. I also think the grad level stats classes and research design classes would be really hard if you didn't have the basic ground work laid out from those classes. I'm not sure for a psyD as I haven't really paid much attention to them.
If you mean you want to take an extra stats class on top of psych stats then I'm not sure. Others probably know more than me, but from what I'm gleaning from this board the admissions people don't really scrutinize what you took besides the fundamentals for psych. They mainly just care about GPA and GRE scores.