You can feed pellets (I don't know about Seramas though- you didn't mention the breed).
They prefer smaller feed, however.
Layer pellets are not good for roosters but a lot of people feed it anyway.
Personally I would feed either Flock Raiser pellets with oyster shell on the side for the layers, or unmedicated chick starter with oyster shell on the side for layers, and some scratch grains daily.
The Flock Raiser has no extra calcium for layers, so would be good for your rooster. Same with unmedicated chick starter. Both are about 20% protein, so you could give some scratch grains too and they would love that.
Back when I had roosters I sometimes fed layer pellets but this is very bad on the kidneys when not producing that egg daily.
What I feed my flock now is grains/seeds and unmedicated chick starter, with oyster shell on the side.