Your mecha for today are the Testa Road, Sky Cats, Mega Diver, Night Walker, and Gran Buster from Battle Skipper. Normally I'd go with the main one but this is a little vague about who that is and doesn't really give too much focus to anyone, so I didn't think that was enough to work with.
Battle Skipper is a toy first series, I was to say something like an advancement on Rock 'Em Sock 'Em Robots. As a result, they're kind of uniquely blocky and inarticulate, which actually isn't bad.
The hero in the second commercial hero appears to be from the manga. I'm not sure if the toys have included lore like Zoids or Gundam, but if it does, I think it would match that rather than the anime. The manga appears to be targeted to elementary school kids, younger than shounen manga.
The OVA, however, is separate. Supposedly it was made based on market research finding that Sailor Moon was popular with adults, even beyond parents. The OVA goes into a shower scene faster than anything I've ever watched, but aside from that and the transformations, it generally seems like it's trying to ape the presentation and tropes from shoujo. I believe it later got a manga in a shonen magazine as well as one drama CD.
Essentially, the company is about power struggles around a family-owned industrial company, a la Tekken. The villain is the heiress of the main family, who seems to engage in crime at a whim. She goes to a private all-girl's school that the company funds, and her club is more powerful than the school itself. The hero are from a club led by a branch of that family, but they're not popular or powerful at all, and instead are barely hanging on. But they serve instead as a vigilante group, having inherited some advanced mecha when the patriarch of their family decided that his conscience wouldn't allow him to submit them to the military.
My biggest issue with the OVA is the second episode. I'll spare you the details, but the plot of that one is supposed to be along the lines of "one of the heroes is tricked into helping the villains", but the way they went about that is genuinely disturbing and definitely not appropriate for what seems to be meant as a very lighthearted cartoon. It doesn't seem like it was actually meant to be shocking, and the major threat in the next episode is "oh no, the school might close down our club because it's affecting our grades", so I feel like it's an issue of the writer having a bad idea and no one there to catch it.