I use my cupcake recipes to bake my cakes(all from scratch) and i would like to know how do i keep my cakes from being too crumbly...i want to make them stackable and carvable. PLEASE HELP!!!

have you tried chilling them in the fridge or freezer before you carve?

I've added a box of pudding and substituted applesauce for the oil.

I'm very new to cake making and decorating, but I let my cake chill in the freezer for about 15 minutes after letting it cool on the counter for about 10 minutes (removed sides of the pan for quicker cooling - springform pan)

I'd say you need to find another recipe. Or tweak the one you have to be moister. Perhanps you are overbaking it?
I suggest you post your recipe so those who do scratch baking can comment on how to change it.

Many people on CC will tell you the best recipe for carving is a pound cake, which is a traditional pound of flour, sugar, butter and eggs and 2 tablespoons of flavoring. The key is to bake in in a slow oven, lining the pans, creaming the butter, gradually adding sugar and creaming them until light and fluffy then add eggs, two at a time, and beat well after each addition.

It sounds like your sponge cake recipe is way too delicate. There are many, many good recipes including the WASC on CC (which can also be used for minor carving as it is more dense the regular sponge). So leave your cupcake recipe for your little cakelets and start experimenting or better yet, ask mom, grandma, or your aunt for their favorite dense cake recipes. I got some great ones that way. I have become the keeper of my grandma's recipes now that my grandmother and mom are both gone. My sisters call all the time for them.

Thank you far all of your help!!!