Im at the Void Quest(old School video game dugeon) boss and Im having some trouble. What level should I be at before even thinking about taking him on? and would anyone know what you get when you start a new game+ do i keep the same level and Persona's or is everything from scratch again/.....IE i havent finished the game yet so please dont spoil anything past the Void Quest dungeon??

you start a new game plus on level 1 but you can buy your personas from the compendium at any level they may be.

If you're having trouble with a boss, try fusing a stronger persona. The personas you equip are more important than your level.

As a general rule, if you're able to breeze through the random battles at the top floors of a dungeon, you're more than capable of beating the boss. If you're still having trouble with the random battles, you may want to keep grinding to ease the boss battle.

Yeah I can actually Pwn everyone on the final floor but after I kill the 2d Sprite and his shadow appears he kills me in like 2 hits (the whole party included)

That shadow has the tendency to use whatever spell one or more of your party has a weakness for.  When he appears guard in order to identify who would be targeted, afterwards attack with the others. Once he starts reforming the robot you can attack with everyone again.

My party to defeat him was Souji, Yosuke, Chie and Yukiko. He attacked with fire... Chie's weakness, which allowed me to cure with Yukiko while Souji had a fire absorbing Persona. Thus... Chie had to defend usual. As long as he doesn't hit a weakness he won't be using his massive devastating attack on all the party.

You need to check your equipment and personas then. With the right persona, almost nothing should be able to kill your MC, especially not bosses.

What spells is he killing you with? Or is it phys attacks? Creating personas that are strong to these things help. Some really good personas are strong against multiple elements and weak to nothing.

It's been a couple weeks since I played the game. You may want to post this issue on the gamefaqs.com boards as you'll surely get a lot of help from people playing the game now like you. The faqs there may help as well.