I put basically no stock in the pump ability, though I guess some prowess-heavy Veyran, Voice of Duality EDH decks or red aggro decks in Constructed might choose that mode on occasion
That means a lot of popular deck archetypes, such as +1/+1 counters and artifact spam, eat particularly well
With Universes Beyond products coming through Standard you can expect they'll come through Arena via Through the Omenpaths or not
But most of all, they just want to solve Magic
I do have some thoughts that might help you, though, but some of these are playgroup dependent (or meta-dependent): From MH3, things like White Orchid Phantom, Estrid's Invocation, Lion Umbra, Glyph Elemental, Indebted Spirit, Triton Wavebreaker, and Monumental Henge all might prove useful
Even if you end up flooded, you can still pump up any of your creatures to make them a decent threat