Tweethe had one fight against rampage who beat him by TKO.
in chuck's defense (i watched that PPV) it was in Japan (jacksons house), in a ring(chuck is a cage fighter and a ring favors jackson, chuck cant stand up off it)
as for rules yeah no more head stomps or kicking a downed opponent. but they gain the use of their Bows (elbows)
rampage will be chuck's hardest fight to date IMO