Didn't expect those Gavan episodes at Go-Busters. I think I watched a couple of Gavan episodes back when I was a kid, I remember some of those songs.
Are the new Metal Heroes movies any good?
Gokaiver vs Gavan is pretty good if you like Sentai Vs movies. It was probably the last great Sentai Vs movie too.
New Gavan is a Osamu Kaneda movie, so it's bad. It has some good scenes, especially the ones with the old Gavan, but the main plot is way too focused on relationship drama and the final action scenes are very underwhelming and short, like usual for Kaneda's movies. New Gavan himself also is a pretty weak character during most of the movie, until the original Gavan straightens him up.
Super Hero Taisen Z, although another Kaneda movie, actually has a better take on New Gavan if you want to see him starring on something. On the other hand, old Gavan is pretty bad here. And well, it suffers from the usual problems of the SHT and Kaneda movies - mediocre battles, unnecessary cameos, some infuriating one shot scenes in the final battle too (It's also a Go-Busters epilogue though).
New Sharivan attempts to be a serious cop mystery with some light hearted references to the original Sharivan series. It has Sakamoto action, and is likely the best out of these movies, although the mystery itself is fairly obvious and cliche. A plot thread is left open here and only closed in New Shaider.
New Shaider is very comedic and light hearted, with a lot of Sakamoto fanservice stuff. The final part of the movie brings New Gavan forward in order to close the plot that starts in New Sharivan.
It's kind of funny though, they've had 4 different supreme commanders for the space police throughout these revival movies.