Platonic Power is the power of kindness.Diol and Poini, according to various sources, have the highest Platonic Power ratings in the squadron. They also happen to be without-a-doubt the nicest, most selfless girls on the team. Incidentally, after Anoa defeats Dark Force/Death Bringer and comments that she's sorry, her Platonic Power surges and she goes Hyper.
- This would also explain why the Bacterians don't seem to be able to harness Platonic power. They're all evil or twisted in some fashion, and thus can't use a power rooted in kindness.
Yuina brainwashed Shiori to pilot Heaven's Gate.For all the people questioning why a normal high school student suddenly dyed her uniform and allied with an invading alien army, how many of them have forgotten that there was a mad scientist who wanted to Take Over the World in Shiori's own home canon as a rival haremette?
Kokoro and her family are from the Lords of Shadow continuity.The main timeline reaches past 2011 (the setting of Excellent) and still no aliens, but no Alternate Continuity has gone past the Middle Ages — so why not? The other represented canons all take place in space and/or in the distant past (save for Busou Shinki, which doesn't have much of a continuity except for the anime, which we know for a fact isn't canon to Otomedius). And Kokoro's comments about her family aren't specific enough to pinpoint a timeline.
The Tripod Core is a Metal Gear.The Tripod Core looks similar to some Metal Gears, so it could be assumed that it's a modified version from them.