Shoryuken! Thanks to 2005 Boards member ProtectronPrime we can report that the Transformers Collaborative: Street Fighter II Mash-Up Ken/Hot Rod vs. Chun Li/Arcee has been found at US Retail.
Following our sighting of the Street Fighter II Mash-Up Optimus Prime/Ryu vs. Megatron/M. Bison 2-pack, now the second Target exclusive 2-pack with Ken/Hot Rod vs. Chun Li/Arcee (redecos of the Power Of The Primes molds, released in Japan in 2018) was found at a Target in Grand Canyon Target, Nevada. You can still pre-order both sets via Target website.
Update: Thanks to the detective work of our very own Nevermore we can confirm that these toys are from a brand new production run for the US market and not the ones originally released by Takara Tomy in 2018.