You would use the fitness team on squad battles not Rivals/WL. I just use fitness cards as got loads at the mo.
For people with more time and no fitness cards a second team works fine.
I use both teams in rivals / WL
my teams are
OTW Anderson - Flash Ibra - Allessandrini (sub on POTM Lucas)
------------ Eriksen -------
----- UCL Allan -- Live Fabinho ----
Live Luis - Future Militao - Sanchez - Live Aurier
------- Flash Casillas ----
From the above I want to upgrade Sanchez to Live version and then possibly upgrade Eriksen to one of his special cards. 3 cards are untradeable so i wouldn't get any money from them if i sold the team (Ibra , Casillas and Gomez)
------- IF Simeone ------
Dybala - Flash Tevez - 87 Gomez
- SMS - IF Vecino
IF kolarov - scream caceres - SBC Skrinrar - TOTY Vrsjlako
--------- Future Lafont ---------
I want to upgrade Skrinrar to his headliner card. SMS to his IF then see what happens with scream caceres if he loses his 90 defending I'll get Manolas or Koulibaly. Again 3 players are untradeable so I wouldn't get any money from TOTY Vrsjlako, Tevez or Gomez.
Both teams play similarly for me. As you can see both my teams are fairly similar in set up and majority of the players are cheap anyway.
Scream caceres is 14K, SMS is like 2K. Allan is 14K and Sanchez like 4K