So, I feel as if my team isn't the best (and I know that it isn't), so I'm hoping that ya'll can give me some advice on how to boost my team.
Team pets (Click pics to view stats):
Aquamarine

Level 64

Bubbles

Level 63

Water Sprite

Level 64

My team is:
-water tank
-light healer
-air dps
I'd use ur max stat as the tank, in any case, with whatever build you decide to go with

I can't say I entirely understand what "tank" means.

If you don't mind changing around the elements and proficiency points, you would have a pretty good team. Water sprite should be your tank, because his base health is 2000, and has 100 base skill points(im assuming someones max stat project?). I prefer shadow tank because they self heal really well with the right proficiency set up. Since he is a level 60 put one point in health, intel and agility. The amount they self heal is based on the damage they do, so always have points in a shadow tanks intel. When he gets to level 65, id put another in intel. Bubbles should be your light healer, because her base stats already favor intel and agility. Put one point in health, intel and agility. Just like shadow, the amount she heals herself and the rest of the team is based on how much damage she does. I like keeping light healers in the second slot since their higher agility avoids attacks and they heal themselves. The third slot, which takes the least damage from enemies, goes to what will now be your Fire damage dealer, Aquamarine. Put her points in...you guessed it...Health, intel and Dex.

Also equipment is super important. you doing alright with trying to keep everything at a legendary level and LG equip, but make sure to try and use stuff that is specific for the element. This is really important for relics, since they actually give a bonus for a specific type of damage. All your pets deal intelligence damage, so you will to get them relics that increase that instead of physical damage

So the tank is the pet that's first in the lineup and the middle pet when fighting (that is to say, the first pet in the Party page but is in the middle spot on the fighting pages)
The tank is the most likely to be hit by enemies, and will be taking the most damage because of that. Therefore, the tank should be:
1) Bulky
2) Hard to hit
Water is good for this, since the majority of abilities block all damage AND heal the pet it's protecting. This is also the reason Agility and Health are the two most important attributes for tanks
Some other popular elements for tanks are:
1) Shadow, because the tank pretty much heals itself, but I don't use that because it kinda depends on how much damage the tank is doing, and hey, you don't have to heal what doesn't hit you, right?
2) Earth, which is what I went with for a long time. Earth makes sure that enemies will hit your tank, and some abilities hurt the enemy when they attack your tank. Super bulky, but having an earth/light/water setup, while unlikely to ever loose, takes literal ages.

That make sense?

Thanks you guys! Can't wait to test this team!