There's none that form the legs.

So the only thing being released are the arms and the head while the legs remain a show only mecha?

It's just semantics, as the torso and legs are both the same piece. The red of the individual teams just attach on top and fold over it.

It's kinda been an issue for a while with the Sentai Mecha for me. They've been focusing so much on collectables and add on mecha that it hurts the base mecha design IMHO. Or they end up kibbley messes.

They are over doing it. I miss the days of a five piece main robo, a sixth ranger mecha, and a base mecha.

Well, we still get that all the time. Well, sans base mecha, which is typically swapped out with an extra large "Final" mecha (Like Cube Whale, Lion Ha-Oh, or the Ushi Origami).
The problem is that they keep simplifying the line more and more so that the main mecha is basic as fuck, the 6th ranger mecha is typically nothing special, and the base/large mecha's interaction with the main robo is basic.

Honestly, the additional add on mecha solves a long running complaint of mech fights being the same thing over and over, as different configurations leads to more variety.

I don't feel that helps all the time, like with Gokaiger.

Boy Gokaiger's robo fights were mediocre as hell.

Well, yeah, there's bound to be some occasions where they drop the ball, especially when they don't take advantage of the variety they're given or just execute it poorly (*Cough*Goseiger*CoughCough*), but it's better than just having the base robo using their super sword attack 50 episodes in a row.