I was able to transfer over one of the quirkiest members of my collection.
This is a VC Mew that was caught using the trainer-fly glitch and made transferable and shiny using Arbitrary Code Execution.
Technically it was acquired purely through in-game means, but it obviously isn't a legitimately obtained Pokemon.
Still, as someone who always liked playing around with glitches in Pokemon games, this is still one of the favorite Pokemon in my collection.
I guess I should be glad Game Freak's hack checks aren't exactly the best.
I have a Zapdos that is similarly special to me.
In Gen 7, I really wanted a Zapdos, but I didn't have access to any event Zapdos and didn't want to play through the entirety of X/Y to catch one. RBY came out on the 3DS virtual console and I figured the fastest and easiest way to get a Zapdos would be to play Pokémon Red and import it up from there. This was before Ultra Moon and the wormholes, of course.
So I downloaded Pokémon Red and started playing it and started to wonder what tricks or tactics I could use to get Zapdos as quickly as possible. I knew about ACE and had seen glitch exhibitions where people could warp anywhere instantly, including inside the Power Plant from Zapdos' exit door, but I wasn't really competent enough at all these tricks to execute them myself. So I decided I would just improvise a path as best as I could.
My path to Zapdos was...
1. Catch a male Nidoran in Viridian City to replace my starter.
2. Arrive in Pewter City and execute Brock Through Walls to skip to Mt. Moon. (IIRC I couldn't walk all the way to Cerulean City with Brock Through Walls but I wanted a Moon Stone anyway.)
3. Arrive in Cerulean City and catch an Abra northwest of the Nugget Bridge, being careful to avoid the trainer there.
4. Use Abra's Teleport to initiate the Trainer Escape glitch from the man in the grass patch. Encounter Missingno to duplicate my Nugget from Nugget Bridge to x128. Then I disposed of one and repeated the process to bring the count up to x255. Repeat the process two more times to bring another item up to x255.
5. Set up the Dry Underflow glitch with the the two stacks of x255, turning the Item Bag in to a RAM reader. If I was smarter, which I'm not, I could have used the RAM in the Item Bag to warp right to Zapdos. Instead I resolved simply to find HM01 Cut so I could get immediate access to the Power Plant.
6. To my good fortune, I was able to find Cut represented in the RAM underflow and deposited one in to the PC, giving me immediate access to Cut.
7. I used Rare Candies from the Item Underflow to beef up my Nidorino, evolved him with my Moon Stone, and beat Misty in two hits.
8. Now I could use Cut and I thought I could go straight to the Power Plant until I remembered the dreaded truth: The Power Plant requires Surf to access. I stood there on the shore and realized that without obtaining Surf
somehow I was going to have to play through more than half of the game, which would be difficult with Item Underflow active. I'd also already done some damage to my save, inadvertently changing my Trainer ID and making my over-leveled Nidoking disobedient to me as a result. If I couldn't find a way to the Power Plant without leaving Cerulean City, I would give up on the whole endeavor and just play normally.
9. The first thing I tried to do was find HM03 Surf represented in the Item Underflow. There were other HMs in there but no Surf, but the items represented in the Underflow
did shuffle around based on where I was in the map. So I walked down to Vermillion and went in to various buildings and spoke to various NPCs to try to get HM03 Surf to appear. But I had no luck.
10. Only one alternative occurred to me, and that was the "Surfboard" from the Red & Green Beta files. This item was mostly just a popular bit of trivia for Gen I Pokémon. It is an item named
????? that allows you to Surf. It was either used for testing (as it allows you to freely surf without the HM, a badge, or a Pokémon) or was a key item dummied out when field moves were introduced. I thought that if I couldn't find HM03, maybe I could find
?????.
11. I hadn't seen
????? anywhere in the Item Bag when I was messing around before, so I decided I would go back to Cerulean and start over in locations with more water. I don't know if there's any logic to this, but I thought that maybe the Surfboard would load when I was around water or around surfable bodies of water. I tried around the Power Plant and had no luck. The only other place I knew one could Surf this early was in Misty's own gym, so I popped in there and checked the RAM and... voila. There was
?????.
12. I ran back to the Power Plant, used the Surfboard to get to the Power Plant, caught Zapdos in a Master Ball from the Item Underflow, then transported it up to my copy of Moon.
That's one of my favorite gaming experiences in my life.