If you only want Wakka's overdrives and aren't fussed about keeping a team going, follow this strategy.

Hire the following players

LF: Tidus
RF: Wedge (Luca)
MF: Letty/Zev Ronso (Luca)/Brother (Airship)
LD: Jassu/Zalitz (Luca)
RD: Ropp (Mi'ihen Highroad Travel Agency)
GL: Jumal (Luca)

Hire those players for three matches.
Enter and exit the BB menu until Attack Reels appears as a Tournament prize.
Play the tournament and win Attack Reels.
Reset Data until Status Reels appears as the League prize.
Hire the same players for thirteen matches.
Play the league and win Status Reels.
Enter and exit the BB menu until Auroch Reels appears as a Tournament prize.
Play the tournament and win Auroch Reels.
Reset Data until the Jupiter Sigil appears as the League prize.
Hire the team for ten matches.
Play the league and win the Jupiter Sigil.