Blend avocado and 2 tablespoons water in a blender until smooth.
Combine 1 can coconut milk, 4 3/4 tablespoons sugar, 4 1/2 tablespoons water, and agar-agar in a saucepan. Bring pudding to a boil; stir in the blended avocado.
Mix remaining 1 tablespoon water and coffee in a small bowl and pour into the pudding. Add food coloring. Scoop pudding into 4 serving glasses.
Combine 1 can coconut milk, 3 1/4 tablespoons water, 1/4 cup sugar, and pandan leaves in a saucepan. Bring custard to a boil.
Mix remaining 2 tablespoons water and cornstarch in a small bowl. Stir into the custard. Add egg yolk; mix well. Pour custard into a bowl; cover with plastic wrap and refrigerate until cool, at least 25 minutes. Divide evenly over the pudding.