The game will not run natively on an iPad, Android or WindowsRT tablet.
So you have two options.
1) Get a Windows Tablet with a dedicated GPU.. problem is there are VERY few on the market.. I can think of that Razer Edge thing and that's it.
740m 750m mobile GPU is about where you'd probably want to look performance wise for a decent but not perfect experience.
http://www.notebookcheck.net/Mobile-Graphics-Cards-Benchmark-List.844.0.html
http://www.notebookcheck.net/Computer-Games-on-Laptop-Graphic-Cards.13849.0.html
http://www.tomshardware.com/reviews/gaming-graphics-card-review,3107-7.html
Small and mobile... you are sacrificing performance and eye candy to achieve this.
2) Stream it from a desktop PC to your tablet... you are entering uncharted waters because no1 has tried it with PvZ and posted about it that I have seen. My GPUs are old and do not have a dedicated decoder... I believe GTX 650 and above models have one.... You would need to look at the specs required for a setup using SplashTop, Limelight, Kainy I think... there are a few more including nVidia's proprietary one (shield/shieldtablet)
You need excellent WiFi for this to work. If you use a Bluetooth controller... depending on the tablet that could hurt wifi and/or the controller significantly. 5ghz will have it's own antenna.. and it's faster.. but it doesn't have the range or penetration.
--------------
Problems either way.. if you are technical minded you can achieve either one but you have to have the right expectations.
