Reset Trading is technically a form of manipulation. HSX has chosen not to punish players for reset trading and has attempted to alter the secret sauce to lessen the damage of reset trading to other players and lessen the profitability.
Coordinated Trading is a form of manipulation and is against the rules. That is when a group of players all trade the same stock at the same time in an attempt to move the price. HSX Staff do have ways of discovering when cordinated training has been done and they do have a way to look at past trades to see if there is a pattern of trading among a group of traders or if just a group of players randomly invested in a certain stock for random reasons (news item posted/stock price moved/etc).