So my Tales experience is vastly spotty, particularly with the last few games due to lacking the (now former) HD Twins (dodges shots)- but I've noticed the obvious and wanted to bring it up.
So the Cameo Battles. Half self-referential fan service, half one the harders fights in every game that has them because of the tried and true fact that opposing playable characters will be harder than any sane boss under most circumstances, simply because they get so many more moves and that much more thought into how they fight. Since Vesperia PS3 is, last I recall, the only Tales game that actually lets you fight the unused half of your party in a straight fight, we usually see this in Tales by how well older characters adapt to new Battle Systems in the cameo battles. Until about Abyss or so, this has been pretty consistent.
Then Vesperia or Graces happened, pick your poison, and something started changing very quickly. I suppose you could call it "hardware-induced power creep", but then Graces' being a Wii games blurs that line a little. The adaptations were not nearly up to snuff anymore; Kratos isn't that much of a boss anymore when the free-run range is enormous and you don't have a spell cue. Grace's cameo battle ends with Hubert's punchline "You know, I thought... you guys would be stronger", ignoring that they chose a really weird trio for it.. Cress and Stahn get a combo attack in Xillia 2, yay, but the Phantasia and Destiny couples move like snails by comparison, even the execution of their artes! The only real option Namco seemed to have was to make them hit crazy hard, as some of them do, but even that only goes so far when your characters have the means to combo circles around them with new mechanics.
For a series with such a long "commercial memory" as Tales- where games over ten years old will get merchandise and magazine space alongside a new year's entry, the recent crossover games, Namco consistently porting even less popular entries to new hardware- I find it a bit of a shame that the core product is a bit of a let down there recently. Like I said, this is all observation and little play, I could be mistakenly reading the exploits of really good players as the norm, but it seems like a bit of a waste; if they could get friggin' Reid to use the equivalent of field of fonon attacks, you could take liberties in later games too.