krekka

reasons:

Ulrich is only powerful inside a computer, krekka can smash anything at anytime

Krekka will eat the power cord to the machines because he thought it was candy rope.

Kanoka disk=win katana sword=fail

Krekka.

Ulrich's sword is useless against him.

He'd have to be in Lyoko.

Once in, how does Krekka get in?

Krekka could smash the computer.

Energy nets can stop human Ulrich from getting to Lyoko anyway.

Krekka wins some generic teen hero anytime.

Ulrich. He is from Code Lyoko. And also Krekka is a moron.