Are the Project X Zone games any good? I was tempted to check out the second one (I think?) because of KOS-MOS teaming up with Fiora, but I never got around to it.
As someone who bought both Project X Zone 1 and 2 recently, yeah I find them both fun. I'd also recommend emulating Namco x Capcom for the PS2 as 1. It's Japanese exclusive 2. So you can easily put on the English patch.
That said in 1 she teams up with T-elos as she made her realize "Hey, we're probably not gonna get home without us working together whether you like it or not." But you don't get them till about chapter 20 though you encounter T-elos quite a lot. Including her threatening to kill the guy from that one capcom game where you're in a zombie infested mall after saying he gets /one/ picture of her since he asked.
I forget when you get KOS-MOS and Fiora in 2 but I think its earlier than Chapter 20. Also you get T-elos and Mumkhar being just the bestest of friends so that's a thing.
Namco x Capcom though has KOS-MOS, Shion, and MOMO but I haven't played past the tutorial (where you get them as well as our main two characters of the X Zone Series) since I got a new computer and have yet to download all my emulators again.
Dunno about Super Robot Wars though where KOS-MOS is also dragged along for the main story and I think T-elos is in one of them too?
Again, though this proves she's the crossover queen of namco.
I know gamestops sell used copies very cheap and still in good condition, so I'd suggest seeing if any of your local ones carry used copies of them.