I mainly used Kasumi for tag in combination with different characters and she is good, can tell you that!
I wont say anything about tiers since i dont know how the other characters play in tag but that is what i found so far.
Pros:
- PPK / PPPK / H+K / 6H+K still guarantee her 6K as launcher or simply tag out for +33
- She can relaunch you to infinity with PKK7K, 6P+K, KK / PP7K, 6P+K, KK / 7K, 6P+K, KK / PKK6K / 33P / 4PKK
- Near a wall you can obviously just cancel the second K of strings that end with 6P+K, KK / 4PKK and tag out
- After a wall splat you can do 33P, 2P, 4PK using 4PK as relauncher and tag out
- Her 236T launching throw leads to insane damage and even to good damage if Kasumi is on her own
(236T, 66, KK7K, 6P+K, K, PKK6K, 7K, P+K / 98 dmg on NH with only Kasumi)
(236T, 66, KK7K, 6P+K, K, PKK6K, 4PKK / 97 dmg on NH with only Kasumi and still has good juggle height)
- Her expert mid kick hold comes in as handy as her throw and can be used for the same combos
- Her 66T which is ok in singles now that stuff like 6P6K ground bounces again is one her best tools in tag
(In singles 66T guarantees 6PK / 6P6K - 6P6K for a ground bounce into a juggle for 75 dmg but in tag...)
(66T, 6PK tag out and enjoy your +33 for a free launcher, full juggle and something around 150 dmg)
Cons:
- She is still as unsafe on block as in singles since you can only tag cancel if the opponent is stunned
- 4H+K being her only usefull sitdown stun that is not a high or part of a string
- Pretty much all her relaunchers / juggles take a lot of space