I kind of love Tricolour because, yes, it's terrible and somehow feels awfully inbalanced against you whether you're attacking or defending (and I genuinely miss how it used to be a part of the Open rotation instead of its' own mode), but working together with players who have a different paint colour to you completely changes how you play the game and leads to all these bizarre strategies. For example, I only worked out in this last splatfest that you can very quickly charge an "opposing" player's Ink Vac. That wasn't the best thing I noticed this time, though.
As an attacking team in Tricolour, you win if either of the two two-player attacking teams have more turf at the end than the single four-player defending team. Because the numbers don't really work out on their own - even if you're working with perfect synergy with your attacking counterpart, half your turf is going to be your colour and the other half theirs, so neither small team individually is going to have enough to beat the defending team - you have access to the Ultra Signal which paints a lot for you automatically, if you can claim it.
But do you really need it? The design on most of the Tricolour maps has given a lot of free turf at spawn to the attacking teams and almost nothing for the defenders. If you can take all the space on your side of the map and the other attacking team doesn't give up too much ground, you can just about win without an Ultra Signal. Just barely, and you need to get lucky with winning fights towards the end of the game, but you can do it.
team Love
I'm not sure how repeatable this strategy is - you really need both players on the other attacking team to realise what you're doing and be nice to you (and they also need to not be trying to pull the same trick because that might get confusing). But it's an interesting way of breaking Tricolour to try.