I battled against Elite Four Agatha first, and now I'm stuck.

I think I'm having trouble using the Radical Cobblemon Trainers Mod. I'm finally battling against the Elite Four members. Excited, I searched for the first opponent, who spawns in the swamp, just like the second opponent, Elite Four Agatha. Without realizing it, I ended up defeating Agatha before battling the first one, who now appears as '???'. I know he spawns in the swamp, but my trainer card no longer shines, and I can't find him anywhere. Can someone help me? I've never used the Trainer Spawner block, and I was thinking of using it now, but I also don't know which item is needed to summon him, since it no longer shows up on my card. I appreciate any kind of help