Not as much as a stab Typhlosion eruption at full health. It's 225 base power. And if the sun is out, it's doubled (Although max base is 255 now >.>). So it's as much as a stab explosion. Whereas, Umbreon's return power can get up to 120 but it doesn't get stab. The best pokemon with Return are normal types, and of them, only ones with good attack and speed. Umbreon, however, is very very very good staller... however, with curse, you could do an Umbreon sweep, if you set it up right. [You're talking to a pro battler ^^ I'm thinking about making a league or joining a tourney in the new cbc ^^]
...N.
SUPAHSRSLY!
It's the thought that counts :3
So in reality, ya can't ^^