There is a bug I found in the most recent 7.0.7 version. When you use the move trick to give a flying type Poke an Iron Ball, it will say that it has fallen to the ground, however ground type moves still will not work.
Every time this happened to me it was after the Poke used U-Turn and then got set back out after, I don't know if that affects it or not but thought I would try to report this bug.
If the Iron Ball is held by your own Poke (I.E. you put it on your own Poke) it will work and ground type moves can hit a flying type Poke, but after using trick for some reason either after they return the Poke and send it back out (which still plays the Iron Ball text) or before that (which I haven't tested yet) the Poke will still be immune to Ground type moves.

Can you try to rephrase it a bit. Like give instructions (in steps) on how to reproduce and then tell what the expected outcome would be.

Let me help with that. I think the bug goes something like this:

1: Start a battle with one side having a Flying type Pokémon with U-Turn alongside any Pokémon in reserve, and the other side having a Pokémon holding an Iron Ball and knowing Trick and a Ground type move.
2: Trick the Iron Ball onto the Flying type Pokémon and then switch it out via U-Turn. (Be careful to outspeed the Flying type even when holding the Iron Ball.)
3: Switch the Flying type Pokémon back in and use the Ground type move on it.

Expected: The move hits as the Flying type gets grounded by the Iron Ball.
Observed: The Iron Ball is shown to ground the Flying type Pokémon, but the Flying type is still immune to the Ground type move.

Yes that is exactly what it is. I apologize for not stating it in a clearer way.

What I’ve been experiencing is the Flying Poke doesn’t outspeed me but uses another move other than U-Turn so I am still able to get the trick to work, the Flying Poke (in my experience it was a Pelliper) will use U-Turn the turn after to switch out.

I then cause them to switch back to Pelliper by sending out a different Poke who knows a ground move, upon the Pelliper switching in the Iron Ball text happens and states that the Pelliper has fallen to the ground.

However once the ground type move is used (in my instance it was Fissure when it did not miss due to no guard) it stated that the Pelliper was immune to ground type moves.

Thanks for the report and the clarifications. I did reproduce this a couple of times, but other times it worked fine, so I'm not sure what the difference was between those occasions. Will attempt to look into it further. If anyone reading this has any further information such as other ways to reliably reproduce then please to post it below.

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