what type/size trowel would i need for 6x6 wall tile and 2x2 mosiac mesh?

Hello dt, Thank you for your inquiry! You can use 1/4"x1/4" trowel for both tiles. It's most important to get good coverage. You want to get 80-85% coverage. Normally you would remove a tile every so often and check to see what coverage you get on the back of the tile and substrate. If this is for a shower, please be aware you cannot install mastic over a waterproof membrane if one was installed. Please feel welcome to call our product support line at (800) 992-6273 if we can assist you further. Thank you for choosing MAPEI products!- Product Advisor #9