imo a tangled team is a team that feels like it'd be nerfed if you were to replace any of its players besides maybe the main duelist.
For example, I think EDG is a tangled team; imagine EDG replacing any of its players, even if you replaced nobody with Leo it'd still feel like a nerf right?
Imo the top tangled teams in val are:
The Guard
NRG
EDG
NAVI (with the exception of cNed)
MXM