Is my phoenix team enough powerful for thrawn/palpa events?

I would also recommend to invest a bit more into this squad. There are much stronger ones, but there are many areas where Phoenix are useful. It will be extremely hard to get Thrawn with them, EP is possible.
You want them Level 85 (after you reach this level), omegas at least on their uniques, and appropriate mods on them (crouchingrancor mod advisor, grandivory mod optimizer, or just google "best mods chopper" for instance).