Possible fix:
Have two phases at start of each turn.
Phase 1: check for effects to resolve or expire
Phase 2: check for effects to apply
Then reword Teebos leader ability to, "All allies have 55% chance to gain stealth at the beginning of their turns (phase 2) if they are not already stealthed. They also have 50% chance to gain 25% TM at the end of their turn."
This allows leader stealth to last one turn and apply the next turn and does not over write his special. If special is used it replaces leader stealth and would not expire next turn.
@EA_Jesse