You should probably already know that purchasing multiple of the same kind of unit will allow them to fuse, creating even stronger units – just as in every other auto-battler, this is important here.
Strength in numbers and synergies:
You can spend coins on expanding the number of units you can put on the field, and this will give you a massive advantage in the early game, and that advantage only gets bigger as the game continues.
I have the high ground:
There isn’t actually any high ground in Auto Brawl Chess, of course that’s just a poor Star Wars reference, but positioning is very important, as in any war of attrition.
Eye on overwatch:
This is an auto-battler of course, so what you do during the battles doesn’t matter too much, but it’s important that you watch closely, especially when you are whittled down to the final few opponents and can see what strategies they use to get ahead.