Vajra is just a kind of anti air assist. I’m not saying that you HAVE to use it. She gets NOTHING off of a random Vajra hit, except for Oki, and that in itself is a risk you’re going to have to take. In this sense, it’s not a great assist compared to if someone like Wesker is using it that gets a full combo off of random vajra hit. If you’re comfortable with using jam session, then feel free. If you’re comfortable with switching to a character that deals with SJ height / fliers, then feel free. What I’m saying, is that if you were to be building a JILL CENTERED team, then yeah, having an anti air answer might be a good idea to have on your team. Sure, you can hard tag or start with Hawkeye, or Mag, or whatever else you want, but I’m assuming you want to be able to deal with this stuff as Jill as a Jill team.
The good thing about Jill is that there’s a lot of ways to make her work. The only thing is she has too many overall weakness that can’t all be covered at the same time. I’ll give you some examples:
Jill / Spitfire / Vajra - (The team that I use) Great mixups, good for keeping the opponent out of the air, can’t snipe assist, the neutral isn’t that great, and can’t get in easily
Jill / Unibeam / Log trap - (Team I used to use) Great way of keeping opponents grounded while getting in, Good for sniping assists, godlike THC with Jill / Ironman, has trouble in the air
Jill / Sentinel / Unibeam - Great way of getting in, solid mixup, has trouble with fliers, cons - have to be able to use Whackbot + Ironmang
Jill / Frank / Vajra - Good DHC, good lockdown with Shopping Cart, Good anti air, neutral suffers from not being able to go in freely
These are the teams I’ve played with already, and I’m having a bit of a hard time finding my own optimal Jill team.
Judging from the characters you’ve listed, weasel shot would be good, daggers for arthur are pretty godlike, if you’re ok with playing anchor Arthur, Paulow uses triple arrows, tatsu is a good assist, I feel like there’s a way to hit at least 700k with it, I just haven’t had the chance to try.