Hello one and all! I would like to briefly go over the new mons in this generation that look very promising for this gen's Cross Evolution meta. I will be talking mostly about the new evolutions for this meta as the evolvers have already been talked about briefly. Sorted alphabetically (mostly). Please mention if I've missed or overlooked anything. Also be aware that this is coming from someone who is fairly new to Cross Evo as I'm not too experienced in the meta.
I will first talk about the best evolution newcomers this gen. I was also going to add the best evolution veterans as well but realized this is way too much for a single post so that will instead come at some other date. Some of the other Gen 9 mons I would've mentioned but are predicted to be banned soon so I didn't count them (ie Houndstone).
Best Evolution Newcomers of Gen 9 Cross Evolution
+Flash Fire / +Weak Armor
Armarouge (+): +45 HP / +10 Atk / +60 Def / +75 SpA / +40 SpD / +40 Spe
Ceruledge (+): +35 HP / +75 Atk / +40 Def / +10 SpA / +60 SpD / +50 Spe
I decided to lump these two together considering they are counterparts and give almost the exact bonuses. This duo gives some very solid additions to any mons who wish to cross-evolve. They do compete for a spot somewhat with veteran returning mons Gallade and Gardevoir but they offer unique options and a more optimized statline to the bevvy of powerful Stage 1 Pokemon that have appeared in the meta. They both give great statboosts, Armarouge actually beating out Gardevoir in this regard, and Ceruledge against Gallade trading in less attack for much more speed, but they also give a very expansive movepool as well as two signature moves that are very powerful as either coverage options or excellent STABs.
That being said, as much as Armarouge seem to be some of the better Gen 9 evolutions, its still going to very hard to beat Gardevoir and Gallade in what they do. Gardevoir still gives a much better ability in Trace, while Gallade, although could have been a toss up in terms of stat boosts and typing, now also gives access to Sharpness, which simply makes it one of the best evolutions in the Gen right now.
+Poison Point / +Water Absorb / +Unaware
Clodsire: +75 HP / +30 Atk / +15 Def / +20 SpA / +75 SpD / +5 Spe
Clodsire, the defensive legend, one of the few mons currently in OU that are able to handle the current explosive threats of the tier. Although on first glance it may seem unassuming as it does not give any new useful defensive typings, it does however give mons excellent defensive attributes with both its abilities, its movepool, and its stats. It can turn a lot of Stage 1 Pokemon into defensive titans, with mons like Dunsparce, Mudbray and Qwilfish-Hisui in particular benefitting the most, and it gives these mons some very much missed moves like Toxic and Recover as well as Spikes. Defensive playstyle however very clearly struggles (I know this from Gen 8), so evolutions like Clodsire probably aren't going to be very common.
+Opportunist / +Frisk / +Speed Boost
Espathra: +65 HP / +25 Atk / +30 Def / +56 SpA / +20 SpD / +30 Spe
Espathra seems like a promising evolution for a couple of reasons. It gives a very solid number of stats for special attackers to make use of, but the real cream of the crop here is Speed Boost which allows for sweepers to snowball very fast alongside their own boosts. Nasty Plot sweepers like Misdreavus in particular very much appreciate the speed boost, and Espathra also gives some very excellent HP as well which means that the sweepers it does support gets some much needed bulk to allow them more setup opportunities.
+Good as Gold
Gholdengo (+): +42 HP / +30 Atk / +25 Def / +58 SpA / +21 SpD / +74 Spe
Gholdengo, probably the best offensive special attacking evolution this gen. It gives crazy stats, an excellent ability, an excellent typing, a very good movepool with an excellent STAB signature, and a lot of the current Stage 1s benefit from it. I honestly don't think much more needs to be said, this is a very stellar edition to Cross Evo.
+Unburden / +Poison Touch / +Prankster
Grafaiai: +23 HP / +30 Atk / +30 Def / +40 SpA / +37 SpD / +35 Spe
Honestly, Grafaiai doesn't seem that good at first glance, and yes it some ways it does seem underwhelming when compared to the other insane mons introduced this gen, but it has one defining attribute that in my opinion makes it a very worthwhile edition to a team, and that is Prankster. Offense is king in this gen, and a lot of mons have access to a lot of set up options and a lot of very strong attacks (with good stats) to make use of. This results in Hyper Offense being the best playstyle by far, and Prankster enables a lot of strategies to make use of. The best that I found was Toedscool + Grafaiai to make use of Dual Screens. Grafaiai also has some essential utility that a mon like Grimmsnarl doesn't have, like Knock Off and U-turn (the latter being particularly relevant over Parting Shot due to Gholdengo).
+Swarm / +Tinted Lens
Lokix (+): +38 HP / +56 Atk / +38 Def / +31 SpA / +30 SpD / +47 Spe
Lokix looks to be a very promising evolution in this meta due to its excellent stat boosts, its added Dark-typing, and its strong ability in Tinted Lens. Lokix gives some very nice priority moves like Sucker Punch and First Impression which also means that Scyther is probably the best beneficiary here. Lokix I see as being one of the better evolutions if you're looking for a good revengekiller, as set up sweepers are for sure going to be running rampant in the meta.
+Chlorophyll / +Hustle / +Leaf Guard
Lilligant-Hisui (+): +25 HP / +70 Atk / +25 Def / -20 SpA / +25 SpD / +70 Spe
Lilligant-Hisui is probably the best offensive physical attacking newcomer evolution this gen. I say this for a few reasons. It gives absolutely bonkers stats with +70 to both attack and speed, it gives the great Fighting-type alongside excellent STABs in Close Combat, but the real cherry on top that completes this mon is Victory Dance. Victory Dance is the physical version of Quiver Dance and just by that description alone you could probably already tell just how broken this move will be. Just a few uses of Victory Dance will basically make a mon unstoppable and a lot of strong Stage 1 Pokemon this gen will very much benefit from a set up move like this.
+Overgrow / +Protean
Meowscarada (+): +15 HP / +30 Atk / +7 Def / +21 SpA / +7 SpD / +40 Spe
Meowscarada is purely on this list due to Protean. I know about Protean's nerf and it does hurt the mons that would've benefitted from an ability like this, but I still think that Protean will potentially find a place in this meta due to Scarf. Scarf Greninja was very much a popular and viable set in Gen 7 and even in Natdex, so I see Meowscarada doing something similar since it also has access to Spikes and a decent amount of coverage options. This unique set of utility is probably still not going to be as good as the other evolutions this gen who simply have an overwhelming power and force, but I still think it's worthy of mentioning.
Revival Blessing - watching a lot of STAB and AAA has generally convinced me that in a format where it's more or less unscoutable, Revival Blessing needs to go. I think UT 
Houndstone/Last Respects - the ability to splash Last Respects on any stage 1 Pokemon is a fairly intimidating prospect to have to deal with. I'm not sure how genuinely oppressive it is especially given the greatly increased number of viable Normal-types running around that could immediately turn a Last Respects abuser into setup fodder, but even non-STAB and unboosted Last Respects is terrifying to face against at max BP without a resist or immunity.
Sneasel - Sneasel and Breloom are both back in this gen, which means Beat Up is also back in business. Given the high Atk stats littering the meta, it's not hard to achieve a 300 BP (after STAB and Technician) Beat Up, which turns Sneasel into a near unstoppable KO machine after a single Swords Dance. Losing immediately because of a bad lead into Sneasel can't be healthy for the metagame as a whole, and there is plenty of precedent from past gens to support a Sneasel ban.
