How X could be represented:
I'd say any graphic representiation of a robot could be X, the nature of BTSX is that they're able to convert themselves into all kinds of currencies, so it can have any robot shape it wants. Different colors schemes could represent different currencies such as blue = BTSX, green = bitUSD, red = bitCNY, orange = bitBTC, etc.
The distinguishing feature could be the "weapon"/symbol as it is for greek gods. In the case of X the symbol could be a giant flag with an X on it, just like the linkin park bot. I think X is the best name for the bot since it makes it possible for the Chinese members of the community to understand the name.
I disagree that the avatar should not be doing anything. The whole point is to have a way for the community to connect with the blockchain, and to make it into something that people care about for more than just the profit. We need all kinds of artwork and ways to represent it in different situations. My wet dream is an end user wallet with a clipper style mascot that then transforms itself into different colours whenever you execute a market order, that would make an excellent wallet to use for microtransactions in games by the younger demographic.
The existence of this avatar would increase the emotional investment into the system, and would thus increase engagement from the average user into community things such as voting.