It is very rare to encounter a Reptile tank in the lower arena (1300-1500 MMR). The most common front Axie is Plant as Tank. They usually sacrifice and tank all the damages dealt in the first 2 rounds so that we can prepare the cards in our 2 damage dealers.
Usually Reptiles are placed at the back because they can sustain and can win a 2 versus 1 situation. He uses STICKY GOO to stun the enemy and invalidate the damage in the first attack.
This is usually a good idea placing the reptile with sticky goo in front since they can sustain and invalidate the damage dealt by Aqua and Beast.
(My Hive Philippines Family)