About Stars... What was Ami doing against Sailor Gamer?
She was powering up and then... Maker attacked Gamer and blew up whatever she was planning to do.
She was gonna upgrade but Maker's forehead was so big that it acted as a reflector and blew her spotlight moment into oblivion.
But more seriously, it's highly likely she was gonna upgrade to either a new attack or form. In 188, Minako theorizes that Chibs might have come to give them (aka the 4 Inners) her power just like in the episode prior, she upgraded Moon.
It seems the staff was flirting with the idea of upgrading the Inners or not and ultimately decided not to, preferring to use their budget for the upgraded Henshin and Attacks stocks of the Starlights.
From the looks of it, each Inner would have had an episode to upgrade;
Ami in the Gamer episode,
Minako in her Idol episode,
Makoto during the Crow onslaught episode (she is prominently featured in this one),
Rei during the Nyanko roof attack episode (again, in this one it's Rei who is prominently featured).
Another reason why this idea might have been scrapped may have been because it was deemed obsolete.
Once Kakyuu appears, we've already entered on the finale storyline.
Introducing new attacks at such a later date for characters who wouldn't get to use them much would be rather unnecessary.