If you attack bot from your level that has 1.0 you get 100% of default energy.
for 0.9 ratio you get 90%, for 0.8 ratio you get 80% etc. For 1.1 ratio u get 110%, 1.2 ratio gets you 120% etc.
It would keep people out from raping low ratio bots, and completely avoiding higher ratio bots, because you might get alot of xp if u rape higher ratio bot, but u only get 500 energy. With this on bot with 3.0 ratio u would get 1500 energy. With that, raping a bot with higher ratio will become somewhat wanted.
Also, adding a level based percentage might not be so bad. It would stop the energy transfer tactic that some people are using now, and most probably, many people will use in future. If you attack a bot that is your level you get/lose 100% of energy. If you attack one level higher and win, u get 110% energy, 2 levels higher should be 120% energy, all the way to 10 levels higher, which would give 200% of energy per fight. All the higher levels would give 200% also. But the trick would be, if you lose, you should lose less.
So:
Attacking 1 levels up and losing - 90% energy lost
Attacking 2 levels up and losing - 80% energy lost
Attacking 3 levels up and losing - 70% energy lost
Attacking 4 levels up and losing - 60% energy lost
Attacking 5 levels up and losing - 50% energy lost
Attacking 6 levels up and losing - 40% energy lost
Attacking 7 levels up and losing - 30% energy lost
Attacking 8 levels up and losing - 20% energy lost
Attacking 9 levels up and losing - 10% energy lost
Thus, attacking a bot that is 9 levels higher than you, and losing, will give that bot only 1 energy.
I didnt think this totally through, but its just an idea to help the game stay on the right track, players fighting other players, not players fighting themselves.