How to reach this score

I tried your opponent's setup out yesterday around 10 minutes before the closure of the Battlez, even with level 5 & level 7 plants, I could only get about 560,000 which is less than 1 tenth of the score.

So I guess the score might have been done as a handicap game with multiplier of 10.

I also agree with Kermo3 that the selected combination does not work at their best, but wanted to have a go to see what score can be achieved.

Killed a good streak I had going...what a let down.

I have seen an image of someone reaching 600+, but this was achieved by paying rather than by playing.

To me, if the streak can be purchased, then it has no meaning.

This combo and the score is obviously a case of hacking.
Look at the score. 6 mil???
I only get 2.1 mil at the max in battleZ, then the zombies are gone.