How in the hell am I supposed to beat Onslaught? 
Get the Fantastic Four, Avengers and Bruce Banner to convert to energy and charge him?
Speaking of which, I really thought Juggy was going to play a part in his defeat as he had been bitch slapped around enough by him. Oh well.
http://db.gamefaqs.com/coinop/arcade/file/marvel_vs_capcom_g.txt has some strategies just for the arcade Onslaught. As I recall in the Dreamcast version these work as well.
That link gives me an error message.