Now the crucial question: power [i]absorption[/i] or power [i]mimicry[/i]? The difference is that an absorbed player's powers would have their powers taken from them, a player whose powers are mimicked would have the mimicking player copy the other player's powers. If it's absorption, no way. That's a good way to kill the game for other players if they can't get their powers back, even if it's possible. Also a no if it's 1:1. If someone with power mimicry can completely copy anyone else's power perfectly, it makes them ridiculously overpowered. Like you intended, Betel, players should naturally come to stalemate if neither player starts with an advantage (say that one player has an environmental advantage or the other player is injured, etc.). 1:1 copy would be a cheap way to get more than one power. Depending on the power mechanics, I'd be alright with the morphing part. A power mimicry character that can only use one power at 1:1 at a time (that being that the player won't even have access to any other powers easily, no swapping mid encounter!) with transforming abilities would fly with me, but if they wanted to hold onto multiple I would say that their ability to use them should be degraded to a fraction equal to that of how many they have/are using. Say, they absorb Ocean's waterbending and Officer Collins's telepathy, the player could only use either to about half efficiency.

Then again, it would depend on how the character was written and how they approach the story. If they're the type of player to be perched upon a rooftop and metagame themselves into an encounter with another player just so that they can fight someone ("Mary Sue just happened to see a passerby sprinting down the street. Suspecting them of being a supervillain, she leaped down from her perch in front of them"), then [i]hell[/i] no. That's a power asking to be abused more than a masochist in an S&M club.

TLDR; I'd have to see how the power mechanics are written up before I cast my vote.