If you have access to the desert you could pick up a Trapinch for an eventual dragon type. Numel and Torkoal can both be caught from Fiery Path fairly early too, if you want a fire type. Makuhita might be a solid choice too and he can be found early on in Granite cave.
You’ve got decent HM coverage already between Wingull, Lombre, and Mudkip so personally I’d replace Zigzagoon with someone else. But that’s just me.
I’ve personally got a lot of issues with it. It feels like the first game stripped of a ton of charm. The story has so many plot lines that feel pointless. The post game gameplay loop is, imo, inferior to the first game’s. Not to mention the lack of variety in not just monsters but gear.
My biggest gripe though was how it just sorta ended. I didn’t even know I was heading into the final boss fight when I got there. It felt like it was meant to be more of a mid game climax but, nope, here’s the final boss.
A lot of my complaints can extend to DD1 as well but the charm of the game helped me get over all of its faults. Handing me essentially the same game with little improvements (and new faults, I’m looking at you dragon plague) was not the move.