@ellavrrr In theory it is possible to have the plants at max level but only by using exploits. However, in this case it is definitely a hacker. As @FantastiXxPVZ pointed out there are some filters that sort out 'high scoring' replays. This replay is not supposed to be in the replay pool...so I'm sure it's a hacker. You usually won't get an opponent who scores more than 20M even though it is easily possible to score 40M+ with Turkey-Pult.
@ellavrrr No idea. My best guess is that this person didn't really hack the replay algorithm but downloaded a mod from youtube to give him/her all the plants at max level. Those mods manipulate the data files in a way that could cause this replay to make it onto the sever.
We don't really know how the anti-cheat system works but a community manager told us that players who are evaluated to be cheaters will be removed from the general Arena player group and placed in their own separate group with other cheaters. Once removed, they will not show up on your leaderboards and their replays will be screened out of the general population altogether. These players will only be matched with other cheater.
I'm not sure if that this is true but in case it is, there is a good chance that the anti-cheat system will detect the replay and move this player to the 'cheaters league'.
