Allright to sommon this up,
as said Damage is = Exp unless the monster is green, red or black. Green gives less where red and black can olso give less exp due to them having more ph def or m def.
Rainbows give more exp from every hit and from the kill bonus
Draggies dont add more exp, but since they make you do more damage it gives more exp that way.
To clear it up if you wanna lvl faster go for rains cause they will help more later in the game 124-127/8 and still do a fine job in tg, where draggies/nix also will help you but when the exp deminishes it wont really do any thing expept if you can one hit lvl 125 stakes at tg.
AND for the record threads like this go in the Co community forum not in a Co hacker forum this is not game support but for hacking/exploits