Great. So not only have they made it more needlessly complicated than necessary but that Katina and Russel aren't actually getting new machines but frames for the old ones.
Actually I'm sort of okay with these. I can just about wrap my head around the 'why' of those multiple skill slots and sticking with frames will at least help stem the power level creep going on (since OGs1 and OGG were pretty bad about that).
Anyways, my take on the multiple skill slots is mostly to encourage splitting up and reforming Twin formations during battle. Say that you have a particular ace that you want to fully take out the boss but of course you'll need to build some Will to use your huge combination attack. However your other high damage dealing ace burns through ammo too quickly or can't dodge for shit (or doesn't want to get hit to avoid Will penalties/ect...) but you still need to build Will for that combination attack. So you start by pairing the two with different partners with skills that compliment their Will building goals (or maybe movement's the issue/ect...), then once you've achieved your desired state you split those two groups apart and reform as one new group (and a dedicated support group with the leftovers) to achieve MAXIMUM DAKKA!!!! Since you only have a limited number of slots you can stick one or two copies of whatever you plan on needing with the aces and have your support carry the rest of the necessary loadout for the Will building ritual (or whatever/ect...) as well as support boosting options for later so that they don't become deadweight afterwards.
In other words its trying to avoid what FE11 did with its Double mechanic where you received bonuses based upon a combination of stats, class, and support level. In effect you're grooming half your active team into support bots for the other half over the course of the entire main game (although with all the grinding you can do in that game and the unlimited A level supports you can make (only one S ranked support though for marriage/breeding reasons) you can easily build a bunch of support options into anybody as well as converting your support bots into frontliners that you can switch back and forth with to abuse things like Lightning Speed or Cry skills).
In the end I think that the three required skills is just for flexibility purposes given that you could either give two units up to four bonuses or one unit up to three out of six bonuses spread across six different partners (provided there are enough skills to go around). Won't know how it goes until we can play it (without importing or resorting to illicit means which I suspect will be between a cold day in hell to never given all the bullshit and general lack of interest that surrounds this series).
