I'm all in for Grookey, but that may only be the case because I used a fire and water starter each of the last two gens. Also, Scorbunny invited you to the party but forgot you even showed up, Sobble is your clueless younger sibling who has no desire to be at said party, and Grookey is your wingman for the entire night who also brought a ton of good snacks. At least this is my headcannon.
The only devil's advocate argument I can come up with in support of random battles is that non-random ones have a passive, static approach to them. You reach a new area and squat, waiting for a list of mons to show up. It's always only a matter of time and maybe weaving around other pokeys before you reach a target. There's a lack of tension and surprise, plus you don't have any input on when/where that rare pokey shows up. Then again, that goes with random battles too. I'm OK with random battles because it's what I've come to expect after 20+ years with these games, but there should be some kind of modifiers so that it's easier to hunt down the rarer ones, especially once you've caught/fought enough common pokeys. Or just give the player some modicum of control over which pokemon show up. Bait, sneaking, grass density, something.