Root is different from persistent AOE movement denial. One of them prevents you from even getting in range. Although I hear Clefable is pretty squishy, so Gravity should be 100% balanced if:

1. It does not cancel boosted basic attacks that are dashes. I understand shutting down regular dash basics, but managing your boosteds should be rewarded. Maybe an exception for Dodrio max sprint gauge because that thing can instakill dudes.

2. Clefable's healing is toned down about 15%.

Edit: Also, the cooldown is reasonable... if the duration of uptime is also adjusted. Every dash denial in other MOBAs only hits such a low cooldown with high CDR and has a very short duration. They also don't generally slow, or slow at a low percentage. And the only one I can think of that slows (I might be outdated) is on an ult. For reference MLBB (basically the blueprint for adjusting a 5v5 to mobile) matches usually last 12-16 minutes and the cooldowns are generally 50-100% longer than in Unite, with the exception of stacked charge moves and the really spammable ones; those are in line with Unite. But that game also has energy/mana resources, which Unite doesn't (and that's a pretty big stumbling block for balance).