We don't currently support "native" trailing stops at Collective2, and due to the processing resources required, we don't have imminent plans to support them.
However, if you are interested in using trailing stops for a strategy that you manage on C2, almost all of the 3rd-party software that is compatible with Collective2 supports trailing stops (TradeStation, Metatrader, NinjaTrader, etc.) -- and so these programs could be used for those purposes.