I"ll post a serious prediction.

Mixed (non-competitive rigged league)
1. Alumni all-star team (skill team or backup lag team) 90% chance win
2. Blackout
3. BTK (if they show up)
4. GTEAM
5. Apostles
6. SL (unless they lose to random laggers first)

idev (competitive fair league)
1. Alumni, Silver, VIS or another good team 25% chance. Possibly a random team that hasn't entered before or hasn't played top 2 before. Who knows in idev league.
2. Impossible to guess.
3. rng