MP campaign Massalia v Rome

[Eidgeniesser]

I'm in a great MP head-to-head campaign with my brother. I'm Massalia, he's Rome. He's slightly ahead but I caught up pretty well. But he'll reach Imperium 5 pretty soon and it will take me 10-20 turns longer.

What do you suggest especially when it comes to army compositions. My border towns with him are Vesontio/ Massalia/ Tingis. We're not currently at war.

Massalia doesn't field Sarissaphoroi. On Imperium 5 I guess I will try to mirror Marian Legions with Thorakitai Kelthellenikoi and the Romanized Thorakitai. But they're probably not as good as the original. As far as I understand the Romans have much better stamina.

Should I still use Epilektoi Massaloi Hoplitai? Are my Peltastai superior? I might get some advantage through celtic and maybe germanic cavalry mercs.

How do I deal with Polybian and Marian Rome as Massalia? Does Rome have any weaknesses? My greatest strength is probably my 25000 Eugeneis (1st class citizens) in Massalia.