Iron Valiant Tachyon Bits vs. Flutter Mane's Midnight Fluttering Rules Question:

[OldGuy]

If a player has Flutter Mane in their active spot and an opponent switches an Iron Valiant into their own active spot, do the 2 damage counters for tachyon bits take effect? Trying to determine if Flutter Mane's ability blocks Iron Valiant's ability or if Iron Valiant's ability takes effect as it moves into the active spot. On one hand, Flutter Mane obviously shuts down the other opponent's active pokemon's ability. On the other hand, Iron Valient's ability seems to trigger by the moving action and not simply just being in the active position. thank you

 

[PokePop]

The Ability is gone once it becomes Active, so it is not triggered.
It would have to be triggered on the bench and move into the Active as part of the effect, but that is not how it works.