Save your explosive flask for Skye. It will slow her down to allow for more precise follow-up hits and will reveal her if you have the "Catalyst" legendary selected.
Tiberius can be damage immune during the whirling blade part of his ult. Use someone like Io or Ash, people who can cc him off the map. He can't use another move until he lands in his whirling blade stance, so he'll fall to his death.