Do you mean like creating new bosses and enemies?
Because I can help in that category.
Click "Edit states", look for the states that have Eggmobile in them, those are boss states, if you want the boss to strafe around the player, then use state 100 - ATK4, find the function A_skullattack (This is the script that has robotnik ram the player) and change var1 to 2 (The variable states what robotnik will do when that script is activated), want rapid-fire missles? Then go to 98 - ATK2, change the function to A_turretfire (or A_superturret fire) and put var1 to 4 (The variable states the object to be shot out of robotnik.).
Don't WANT the ram attack to happen, but instead shoot bomb rings and such? Then go to 102 - panic2, and change the function to A_fireshot (or super) then change the var1 to 123. (Tells what object to shoot.)
Hope that helps.