I'll help you out:
While it was heavily implied not 1,not 2 but 3 versions of Battle of Gods that Base Goku in BOG was still weaker than Freeza [Pre Training].How would you explain these things ?
* Vegeta being confident on winning the TB even if Piccolo is participating.
Chapter: 430 (DBZ 236), P6.5-6
Context: after Gohan asks that nobody becomes a Super Saiyan in the tournament
Vegeta: “…Well, I guess that’s fine. If nobody becomes a Super Saiyan, then the conditions are the same. My superior position doesn’t change…”
* Base Goten and Trunks [In Mighty Mask costume] putting up a good fight against Android 18.
* This line by Dabra
Chapter: 447 (DBZ 253), P11.1-3
Context: talking about how Yamu and Spopovitch were followed by Goku and co.
Dabra: “Seems they’re trying to hide from us…In total…there are 7. We can’t use Kaioshin and Kibito’s energy…But 3 of them [Goku,Gohan,Vegeta] seem to have marvelous energy…”
Babidi: “Looks like it. It seems that we’ll get more than enough energy from just those 3…Kuhihihi…To think that we’d be able to revive Majin Boo so quickly…”
The Counters:
The first statement is clearly only talking about the Saiyans. Vegeta is merely saying that if none of them use SSJ, then the respective gaps in their power will stay the same. It's actually a fairly strong argument for SSJ being a multiplier that I had never really considered, but oh well. Vegeta's goal here is to beat Goku; he doesn't care about the tournament.
As for 18 and Mighty Mask, 18 does want to win the tournament. She, however, can't sense ki, so she has to keep herself restrained in order not to kill any normal people, which would result in her being disqualified and not winning the tournament. The issue with Mighty Mask is that she has restricted herself to fighting normal Earthlings, and MM is much stronger than that.
As for Dabura, he thought Pui-Pui would beat Vegeta. Who cares what he thinks?
Kaioshin also seems to be scared of anything with Majin stamped on it. Piccolo is established as being stronger then Base Saiyans but weaker then Kaioshin. This remains factual and Kaioshin was scared for no reasons other then strength alone.