Having a character who knows all martial arts, and being able to write effectively with those moves are different things. The way I personally look at is, "Hey, that's even more material for me to work with!"
Three fighters in particular have copycat abilities, one of them hopes to steal a move from me, however, he will walk away disapointed because of clever writing on my part. Another has already stolen all of my moves, and intends to use them against me, and again for him I must use clever writing to win. I don't anticipate problems though, these people assume that a ultra powerful bio automatically means an ultra powerful FC character. In truth, the abilities of the FC characters are limited by the vivid imaginations of the fighters. With those two characters, as long as you can describe a better fight with the same abilities, then you've won. In one of my better fights, I wrote in the defeat of my character . . . but I still won. Just use your imagination and play in the rules.