Because you have not specified any particular Infrared nor ultrasonic device only generic responses possible.
Infrared range finder devices which triangulate normally project a small focused light on the target. The receiver likely is only looking for the refection in a defined area. So interference from reflection of other infrared signals should be unlikely. However, if an infrared source was aimed at the receiver, it could flood it and cause an incorrect reading. Since normal transmitters project a small focused light, this too should be unlikely. But if the opponent wanted to, it may be possible to flood the play area with correctly modulated infrared light.
Ultrasonic range finders transmit and receive sounds waves timing all events. So there is only a small window when the range finder is expecting to hear an echo. Any sounds heard outside this window of time are likely ignored. It would appear unlikely that two independent ultrasonic range finders would encounter overlapping windows where they would be susceptible to unexpected interference. That said, it may be possible to flood the play area with the correct ultrasonic sound to cause the opponent problems.
Software solutions exist to deal with unintentional interference. Values that are known to be impossible can be rejected. Minimum of, say, 3 samples and Maximum of, say, 3 samples can be used to remove outliers. And averaging can be used to remove noise.