From "Timebokan Series Yattodetaman", the giant robot Daikyojin & Daitenba appears in RIOBOT series!!
Daikyojin can transform into flight mode Kyojin-go, while Daitenba can transform into tank mode Daitenba Sensha.
Furthermore, by combining Daikyojin and Daitenba, you can reproduce Daibajin and Daibajin Sensha form.
Daibajin has two ways of combination, by folding up towards the back like toys from the past or by removing the legs as in the anime.