Some good stuff here, and some bad stuff here.
First, a minor rant. Why do wizards always get all the spells? There are only two spells from this list that Wizards don't get. Summon Bestial Spirit and Summon Celestial Spirit. They literally get every other spell here, that sort of thing just annoys me.
Looking over the actual spells, most of them are fine.
Acid Stream is neat, giving us a damage over time effect, it is all or nothing for only 3d4 damage, so maybe it needs a tiny buff? I'm not sure but if it hits and the enemy wastes a turn preventing the damage? That's good. If they don't, that works too.
Otherworldly form is a bit... It feels kind of useless. Clerics, Warlocks and Wizards get it. It gives a medium fly speed, and additional AC which is nice. Some damage immunities which are cool if you can match up to the right type. All of your attacks are magical and use spellcasting is... ok, but 6th level spell means 9th or 10th level. Extra attack could be useful?
So, who wants this spell is the problem. Blade Pact locks already have magical weapons, getting to use their spell attack might be good, but they already have extra attack, and since this is a melee leaning spell, the fly speed is less useful. Clerics? Clerics can get a lot of use out of this really, they generally end up in melee and have good AC that this is buffing, but they either have a good melee option already or they built to not go into melee which makes the extra attack less useful. I don't see many wizards at all thinking this is useful.
Spirit Shroud is similiar. Decent for Paladins and bonkers for Bladelocks, but less so for Clerics and Wizards. I really like the fact that is shuts down healing, and bladelock auto scaling leads to this doing 3d8 extra damage per hit, which is really something. Plus lowers the enemy speed. Heck, even Clerics might like casting this at higher levels and combining this with Spiritual Weapon. Just a great spell.
The summoning spells are hard to nail down, some quicker thoughts.
All the scaling is pretty similiar, so if you cast the spell at the same level, the monster is within 1 or 2 points of each other in all stats. Which makes comparing them easier at least. Also, all of them get multi-attack. 2 attacks for 4th and above, 3 for 6th and up, up to 4 attacks a turn if you cast with an 8th level spell.
Aberrant is amazing. The Slaad regens and shuts down healing, the Star Spawn has an Aura of damage, and the Beholder can fly. Short ranged attack is a problem, but this thing gives some great options
Bestial kind of sucks. They get no special abilities except for the flyby attack or maybe pack tactics. Just very generic.
Celestial is amazing if you use Defender. Hits hard, grants temp hp on every hit, this thing is a massive tank. You can go ranged with the Avenger, but I don't see a great reason to do so
Elemental kind of sucks compared to the others. Some resistance, but they just run up and hit. Nothing really interesting to use them for.
Fey... also kind of sucks. They get a melee attack only, and their specials only activate when they teleport. Furious grants 1 attack advantage (woo?), Deciet gives 1 space of darkness every time they teleport, Joyous is actually interesting for giving charmed, which prevents someone from attacking them, but they just don't get anything else to make summoning them worthwhile compared to the other spells.
Fiend is amazing. 1st, all of them get magic resistance which nothing else gained. So, the basic plan is Devil. The Devil sight is probably not worth much, but fly and hurl fire is solid damage, especially at 2d6+9 and three attacks. Second plan is demon, run it, hit harder and then blow up for damage. But, yugoloth is sneakily amazing. Only hitting for 1d8+9, but after every attack they can teleport 30 ft, so they can bounce around the battlefield like crazy. I'm not sure it is powerful enough to stand against the benefits of the other two combined, but it is a solid ability to hit so many different targets in succession.
Shadow hits like a truck with 2d8+6. The scream is meh. Fury gives you advantage if you use the scream or build for it, but that is going to be unlikely unless you really work for it (best sysnergy would be with a Conquerer Paladin which can't get this spell). Fear gets stealth which is nice, but Despair slowing any humanoid by 20 ft for being next to it is just a massive stickiness factor that I love. You probably can't actually escape a Despair Shadow, because if you dash for 20 ft of movement they just catch up and hit you again, while also getting an attack of opportunity. They are scary good.
Undead again has some nice things. The Ghost is incorporeal, flies, and can frighten on every hit. The Putrid can poison if you start near it, and then paralyze you if you were poisoned and fail when it hits you, turning every other attack into a crit. Which is brutal. Skeletal gives you a hard hitting ranged option, but is probably the weakest of the three. Still, one of the only ones with as many cool options as Abberrant.
Also, quick list of who gets what.
Aberrant (Sorcerer, Warlock, Wizard)
Bestial (Druid, Ranger)
Celestial (Cleric, Paladin)
Elemental (Druid, Sorcerer, Wizard)
Fey (Bard, Druid, Sorcerer, Warlock, Wizard)
Fiendish (Warlock, Wizard)
Shadow (Sorcerer, Warlock, Wizard)
Undead (Warlock, Wizard)
So, Warlocks and Wizards are the big winners here, with Clerics having a nice option or two. Oh, and the other classes got participation awards (Sorcerer is actually in the running, getting Aberrant and Shadow, but missing out on Fiend hurts)
Tattoo magic is nice, I like the idea of getting multiple effects counting as one attunement, and some of them are really good. Absorbing can be tide turning if you take the immunity and healing at the right time. A lot of good ones actually.
The only one that seems actually bad is the Barrier tattoo. They essentially give you studded leather, half plate, or full plate but only if you don't wear armor. So, the same sort of calculations go in, and since half-plate is way cheaper (and most monks are going to have a better wisdom than 14) most of these options are just not good for most characters.