I think it’s the conclusion of the Guzzlord plot and I think that they are hiding the title is because Dia and his Zeraora are coming back to help Ash and company defeat it.It's to early to tell at this point. It could be anything from the masked royal or conclusion of the guzzlord plot to the awards ceremony and post league celebrations.
I think it’s the conclusion of the Guzzlord plot and I think that they are hiding the title is because Dia and his Zeraora are coming back to help Ash and company defeat it.
His first option is to use one of his reserve members to fill the 6th slot. But the question is which Pokémon does he use? He has 6 regions worth of Pokémon, not to mention his herd of 30 Tauros. How can he choose one of them without making the others feel left out? And no, I don't think that he should just go with Pikachu, Torrecat, and 4 reserves. It wouldn't be right to leave out Rowlet, Lycanroc, and Melmetal, just to hope that he can win with his reserve team. So I think that it would be unlikely for him to use any reserves.
It would have to be a pokemon in its first form Pokémon to be that possibility
His second option is to bring back Poipole. However, Ash would have to rely on luck to have Poipole come back in the previous episode, as part of their attempt to take out Guzzlord. If Ash and his friends take out Guzzlord without Poipole coming back, then if Ash wants to get Poipole, then he would have to find Solgaleo, convince him to open up an ultra wormhole to Poipole's ultra space, find his Poipole from the entire group of Poipole (though that may be easy if Poipole remembers Ash), and convince it to join Ash's team just this one time, go back, have his full battle, then reopen the Ultra wormhole, and return Poipole back to its Ultra Space. So if Poipole doesn't return in episode 140,then it will not be likely for Ash to use Poipole for the full battle.