Tackle is not necessary on any build.
In PvP it is nothing more than a poke or combo finisher. It hits damn hard, so if you're thinking you're going to be able to initiate a juggle with it, you're going to be disappointed. The damage it deals goes directly towards the juggle cap, so the opponent will fast fall after like two more hits.
Get level 1 if you must; I've had great success with it, charging through everything for a 5k tackle and 3k suplex. It makes people QQ very hard.
But it's not needed. And definitely not maxed. Since it's %-based, you can leave it at 1. It's not going to be a big damage dealer in either PvP or PvE.
Intense Takedown is a must on any build, no exceptions. Even in PvP, grabbing the shit people leave out on the floor means you can do long-ranged pokes. Landrunners, Hodor, summons, things that proc from equipment (which people REALLY shouldn't have on in PvP), pretty much anything an Exocirst puts out (they hate it so much lol!). In PvE, it will double your damage. Makes shockwaves so damned huge it's not even funny...
My two cents.
Also, max Grab Mastery. You're gonna want as much QQ as possible from the opponent when you use your grapples. People HATE missing, but you will LOVE when they do, especially when Irresistible Grab is down and you're sliding at the enemy like a ton of rocks. Why wouldn't you want people to miss you when you use the most irritating skills in the game?
God I just looked at your build, 'tis a mess.
Seismic Punch must be maxed if you're ever planning to use it. It's a really, really bad skill. It has no hitbox until you hit the floor, so you can be hit out of it pretty easily, it flies a set distance so you'll never land it more than once on anyone not retarded, and it needs full investment otherwise the delay will kill you. Some people like it, so don't. I don't, obviously. You won't use it unless it's maxed so don't get the cancel.
Muse Uppercut should be maxed... I don't need to bother explaining that, it helps you juggle.
Your big three-- Wild Cannon, Spire, and Cyclone Suplex should be maxed. Most of your damage will come from these skills.
Elbow Shock is there for an extra attack while the enemies are OTG. It doesn't scale well in PvP and in PvE, you have much better things to spam. The shockwave is the only thing fixed on the skill, and that is irrelevant in PvP.
Neck Snap should be level 5 + Cancel. It's Grappler's single nod towards on the floor combos. It has an extremely long hitstun, and it's super fast, so you can essentially do XXX > Neck Snap > XXXX > Juggle. Doubles the amount of hits you can land while the enemy is standing, and that's damage that doesn't count towards the juggle damage cap.
BACKSTEP. GET IT, USE IT, LOVE IT.