Tank Team

Anyone can explain the term tank team which used in most tournament events??? does that mean putting a high hp character in that team instead of putting your main team?? o.O

It’s usually talking about a very low level team being used after reaching a certain point in tournaments.
You get a set of rewards you were hoping for then switch out to the tank team to actually tank in points and reduce your Matchmaking Rating/MMR.
Tanks(High Hp Chars Ares/Hulk/Thor) =/= Tank Teams(* teams or Bagmen/women).

O.o why would we use lower lv covers which will lead ppl to attack us and lose o.O??? and how does it reduce ur MMR in tat way? ><