Witness Genesect! (Japanese: ゲノセクトを目撃せよ！) is the fourth Pokémon Tretta set. It features 48 Tretta.
Witness Genesect! features the Legendary Paleozoic Pokémon Genesect as a playable Pokémon for the first time in Pokémon Tretta, after appearing as a possible opponent in Challenge Cup events held prior to the set's release. Genesect is also one of two Pokémon to introduce the Bugtype to Pokémon Tretta. The Legend-class Tretta for this set rounds off the Tao trio with Zekrom, with Kyurem and Reshiram included in the last two sets.
The Combo mechanic continues, though all Tretta featuring it have a icon as opposed to from the last set. Tretta with can still perform a Combo with each other, but not with those with . A new Form Change mechanic was also introduced, which allows the Pokémon depicted on Tretta with a icon to shift to an alternate form in Round 3 of Battle Mode. The starting form is present at the top of the illustration on each Tretta. After changing form, Pokémon retain their type and stats, but have access to a new move in place of the starting one.