I was reading the page on the GSX Sentinel Mark II and people were talking about new rules for Colossal Figures. I've downloaded the rulebook off this site but can't find anything about Colossal Figures. What are the rule changes for Colossals vs. what they were in say, 2007?

the pac and players guide will give you more info.

You'll want to check the PAC for Great Size and Colossal Stamina.