Now, it's not specifically the fights that I'm picking on, nearly all of the character animation is really bad throughout the entire show and I don't really like the designs anyway so that's two bad things coming together in an unfortunate manner. It really looks like Sunrise spent practically no money on this series for reasons that I cannot fathom. 90's Sunrise produced some pretty good looking stuff as well.
You need to look at GaoGaiGar's context. If you compare GaoGaiGar to the previous Brave shows, you'll notice that the animation is more fluid, has much better shading (Really, it was very common to get no shading at all on those previous shows) and the battle scenes are longer.
Of course, that came at a cost considering how they likely didn't have a higher budget for GaoGaiGar. They basically made stock footage for every single attack of the hero mechas, rather than just the finishers and combinations, unlike in the older Brave shows and reused that same stock footage throughout the entire series.
Here's an example of what I mean, regarding the previous Brave shows.
Here's the Might Gaine in stock footage:
Here's the Might Gaine in a still shot used once:
Here's the Might Gaine actually moving around or attempting to do things:
When you added any action, the models were often greatly simplified and most of the shading disappeared. GaoGaiGar kept things mostly on model and had much better shading, but at the cost of having to reuse stock footage every time for almost everything aside from some rare episodes.
People should watch Yamato.
I wonder what they'll do with her if they start remaking Yamato 2. The original male Yamamoto was pretty much a background character in the original series, so they can do anything with her without changing things up, but Yamato 2 liked to randomly put him in the spotlight just to spit on him. Although, I guess they aren't likely to go beyond the original series without heavily changing things up.