Like with figures, Dialga has recieved almost too many random flats over the years. At least the massive amount of them means quite a few will be more interesting to me.

Dialga , Palkia & Darkrai Sticker
Manufacturer: ??? (Japan)
Product Line: ???
Release Date: 2007
Purchased From: PKMNCollectors
Given out to promote the Darkrai movie. I really like the art used for Dialga here as the pose seems to be new; Palkia and Darkrai weren't so lucky.

Dialga DP26 Jumbo Card
Manufacturer: The Pokémon Company International (USA)
Product Line: Diamond & Pearl TCG Series merchandise
Release Date: August 15 2008
Purchased From: eBay
This was included in the Dialga Premium Box, along with a theme deck, some booster packs, and the standard print of DP26. There's also a Shattered Holo version out there, which I'd really like to find.

Dialga BW Kid Figure Sticker
Manufacturer: Bandai (Japan)
Product Line: Pokémon Kids Best Wishes ~Mewtwo Hen~
Release Date: June 11 2013
Purchased From: Pokevault
Kid figures used to include a sticker with each one in addition to the usual candy. Really wish that they'd go back to that.

Dialga Plasma Blast Booster Pack Sleeve
Manufacturer: The Pokémon Company International (USA)
Product Line: Black & White TCG Series merchandise
Release Date: August 14 2013
Purchased From: Who knows?
One of the few things I got as a kid that's still in good condition. Really surprised I still have this, but I'm certainly not complaining.

Dialga & Palkia 2018 Legendary Pokémon Code Card
Manufacturer: The Pokémon Company International (USA)
Product Line: N/A
Release Date: February 2 2018
Purchased From: Gamestop
I have a few of these, both used and unused. I really wish that more events were given out this way; it's just more fun like that!

Cosmic Eclipse Elite Trainer Box Items
Manufacturer: The Pokémon Company International (USA)
Product Line: Sun & Moon TCG Series merchandise
Release Date: November 1 2019
Purchased From: Target
All of this was included in the Cosmic Eclipse Elite Trainer Box. I used to have all of the sleeves, but ended up using them all after a while.

Cosmic Eclipse Build & Battle Box Flyer
Manufacturer: The Pokémon Company International (USA)
Product Line: Sun & Moon TCG Series merchandise
Release Date: November 1 2019
Purchased From: Gamestop
This came with the Build & Battle box released for Cosmic Eclipse. It has a little description of the set on the front, and some tips for playing the game on the back.

Dialga Mezastar (7-Eleven Purchase Campaign)
Manufacturer: Takara Tomy A.R.T.S. & Marvelous (Japan)
Product Line: Mezastar Promotional Tags
Release Date: November 20 2021
Purchased From: eBay
I assume these were given out to tie in with the release of Brilliant Diamond & Shining Pearl. I love the way the translucent green looks, it makes it stand out a lot more than the plain grey used on normal tags.

Chimchar & Dialga Mezastar (2022 Happy Meal)
Manufacturer: Takara Tomy A.R.T.S. & Marvelous (Japan)
Product Line: Mezastar Promotional Tags
Release Date: March 4 2022
Purchased From: Mercari Japan