p
Tank
Tanks are a difficult role to really limit Lifeweaver's potential.
Tanks, much like DPS can benefit from Parting Gift quite a bit. Winston, Doomfist, and Wrecking Ball are going to thrive with some coordinated attacks on Lifeweaver. That said Rejuvenating Dash is something more mobile tanks need to keep track of.
Heroes that rely too heavily on barriers like Reinhardt and Sigma might find a decrease in value against Lifeweaver. This is primarily due to his ability to arc his Healing Blossom over enemy barriers.
Junker Queen has an interesting gameplay loop to follow as well where her knife could be used to negate Life Grip. Additionally, Rampage's ability to shut off healing is incredibly valuable. With the reduced amount of Kiriko we've seen, the queen might be back on the menu.
Also, stay away from Orisa. Petal Platform is a huge counter to her ultimate and Life Grip can save a target from Energy Javelin.
For counters specifically, we'd recommend the more agile class of heroes. Your Winstons and Doomfists should be able to follow Life Grips quite easily and chase down any pesky Lifeweaver in the backline.
Support
Ohhhh boy, now we're cooking.
Supports are going to offer some of the biggest counters to Lifeweaver.
Ana? Biotic Grenade obviously shut out any healing, but it will persist through Life Grip. When Lifeweaver is in your ranked games, that cooldown is going to be a big impact-maker. Being anti-naded is going to make the following Life Grips infinitely easier.
On top of that, Lifeweaver's low healing throughput really is going to make topping your teammates up fairly difficult after a big Biotic Grenade.
Lucio and more importantly Birgitte, after her new rework, should be ready to make plays. Displacement is going to be a huge in both shoving Lifeweaver out of range or his targets away from his reach.
On top of that, there is something to be said about the height of Petal Platform and the ability to knock people off and away. Some unintended environmental kills are bound to happen this season with the introduction of more vertical options for heroes.
Zenyatta might be a difficult sell here due to how Lifeweaver can quickly move Discord Orb target behind barriers and cover.
Counter wise, we'd recommend Ana, Lucio and Brigitte 2.0