The CG official images make the toys look gold and purple, but the actual toys are yellow and purple, so I wonder if they were originally planned to be more golden colour.

I am still trying to work out what the toys are standing on... the colour makes me think of ER Scorponok, but the shapes make me think of TR Trypticon (I haven't had a chance to dig them out yet to look for those specific panels).
Never mind... apparently it is ER Scorponok's tail.