Transformers 2 writer Roberto Orci has answered a question on Don Murphy’s board, in the “Hey Roberto” thread, mentioning a new feature in the sequel:
Roberto, will there be Transformers that transform into Weapons in TF2?
yes!
As some of you may have noticed, the Transformers 2: The Ultimate Battle game description mentioned a new transformation system, including weapons. If this turns out to be true, and not a complete bluff, it will add something different. It could be that the bot that turns into a weapon is part of the larger robot, like Scorponok in the first film.