Answer
YRI; YRi; Yri; yRI; yRi; YrI; yrI; yri
A Punnett square with 64 boxes (8 combinations above on each side, so 8x8=64) would be needed.
Work Step by Step
To get this answer, simply go systemically through all possible combinations for each gene being dominant. The size of the square is always the number of possible alleles squared.