Pteramander
Creature — Salamander Drake
Flying
: Adapt 4. This ability costs 
less to activate for each instant and sorcery card in your graveyard. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)
Simon Dominic
Ravnica Remastered (RVR)
• #317Rulings
If a creature somehow loses all of its +1/+1 counters, it can adapt again and get more +1/+1 counters.
(wotc • 2019-01-25)
Pteramander's activated ability can't reduce itself to less than {U} to activate.
(wotc • 2019-01-25)
You can always activate an ability that will cause a creature to adapt. As that ability resolves, if the creature has a +1/+1 counter on it for any reason, you simply won't put any +1/+1 counters on it.
(wotc • 2019-01-25)
Rulings
If a creature somehow loses all of its +1/+1 counters, it can adapt again and get more +1/+1 counters.
(wotc • 2019-01-25)
Pteramander's activated ability can't reduce itself to less than {U} to activate.
(wotc • 2019-01-25)
You can always activate an ability that will cause a creature to adapt. As that ability resolves, if the creature has a +1/+1 counter on it for any reason, you simply won't put any +1/+1 counters on it.
(wotc • 2019-01-25)