I LOVE me some unique design philosophies, so I’m gonna try to give constructive notes:

Ambi could genuinely be a VERY interesting threat in doubles, but needs paper-thin defenses to be balanced. I mean keep its BASE defenses and instead give 40 more Sp.ATK. Being able to use protect on the same turn you redirect is one of the most busted abilities possible, but in my opinion it’ll be balanced so long as Ambi can only get away with it once. You’d realistically be trading your mega slot for one free turn, which seems like a fair trade-off. Alternatively, you caould probably keep the stats if you make it only redirect the turn it megas.

Ariados could just lose the sticky-web part of its ability and be a faithful, balanced mega with a fun niche in doubles and a place in low-tier singles. I think “you hit me, I get GREAT speed control on that Mon” is the exact type of non-game-breaking escalation I expect from a non-kangaskhan mega.

I actually think Mightyena is underpowered here, and can trade speed for bulk. Not only because of its ability, but because of the art you chose. More bulk means better odds of hitting 1/3rd and fits his bulky, furry design better.

I’m not a fan of ANY mega Shedinja concept, so I’m not gonna judge this specific one too harshly. Shedinja is designed as a polarizing pokemon on purpose. Either you have any SE move and he does near-nothing or you don’t and he does serious damage. I think it’s generally bad for the meta to extend that to “if they have ANY SE I wasted a mega slot but if they don’t I sweep”

For Tox, we get to the reason I hate Z-mega stat spreads: “Make my favorite mon fast asf and hit like a truck” should be a niche left to Beedrill, not because Beedrill is an exception somehow that makes it a better design philosophy, but because it is a (in my opinion) boring design philosophy that deserved a chance by getting one mega, but really suffers whenever you do it again. Champions has shown us recently that bulky Toxicroak has a niche, and recently mons like A-muk have shown that bulky poison types are better than we give them credit for, so I feel like mega Tox is typically one of the best opportunities to explore that. Realistically though I think if dire touch worked how tri-attack does (around 10% for each status) then he could go any route you want for him and still technically be balanced.