If you can have a “buffer” of a few hours between the green tea caps and the Indigo, that’d be the safest bet to avoid any overlap. So like, green tea stuff in the AM and then Indigo before training in the afternoon should be fine. But if it’s some big formula that has a small amount of EGCG (green tea) in it and no other antioxidants, you may be able to take them at the same time if you wanted to train in the morning.
Though, if you’re looking for a “caffeine tablet type of thing”, would it be crazy to consider just NoDoz or Vivarin? Super cheap, just caffeine (definitely more than you’d get in any green tea supp), and no problems at all with Indigo.