A Megatron-led Mardu deck gets access to one additional Cybertronian over the Jeskai version, and while you do lose out on some of the more elaborate interactions, you also dont need to do as much work to enable Starscream and Blitzwing as you do to get value from Goldbug and Jetfire
Like most Pokmon cards, the value of Sabrina's Porygon depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (Gym Challenge)
Anyway, here are some of the Koa'ki Meiru monsters that can be useful for this deck (you don't need to use all of them): Boulder, Crusader, Guardian, Hydro Barrier, Rooklord, Sandman, Urnight, and War Arms
V-UNION Pokmon are made up of four separate Pokmon cards, in a similar fashion to LEGEND cards