Not the sequel. Not the freemium version. The version of Plants vs. Zombies is a masterclass in tower defense. On iOS 9.3.5, there are no ads, no microtransactions, and no "energy" timers. You just play Zen Garden, Adventure mode, and Survival Endless. It is perfect.
If a popup appears saying the app is incompatible, it should offer to download the "last compatible version" for iOS 9.3.5. Important Compatibility Notes games compatible with ios 9.3.5 ipad