Hello there, darling! I thought I saw a support card for a neglected archetype, and what do you know, I did! Let's try to review this, and also correct your PSCT as it appears to be rather off.
To start with, the first effect of this card is quite reminiscent of Cloudian Squall. Did you take some inspiration from it, perhaps? That's great, because it's a crucial card to that archetype's counter-based playstyle, so of course this archetype should have something similar! It being a field spell also means you can't distribute 2+ counters per turn like Cloudians can, with the tradeoff being that A-Counters tend to be a bit more disruptive than Cloud Counters. The activated effects however, may come a bit too cheap.
Full effect immunity for a selected monster doesn't sound too bad, until one realizes that this is any monster. It doesn't even have to be an Alien monster. If, for instance, you were to summon a powerful boss monster who can't be destroyed by battle or some such, this makes them perfectly unkillable (aside from Kaiju tributes) in all but your most dire of circumstances or until the field spell is removed. The Special Summon and searching effects are quite alright though, and I'm not quite sure what how valuable non-targeting, non-destruction removal is in the current climate so I'll refrain from suggesting a different cost for that.
Overall, you may want to tweak some numbers with the card's effects or the effects themselves, especially when none of these effects have a HOPT clause like many cards do these days. It's quite a fine idea on a field spell for Aliens that isn't the rather underwhelming Otherworld - The "A" Zone, though, so don't feel discouraged. I can't help you tweak those numbers or effects, but what I can do is correct your PSCT, as it has a few outdated words/phrases and quite a few grammar errors. Ahem.
During your Standby Phase: Place 1 A-Counter on every face-up monster. You can remove A-Counters from anywhere on the field to activate 1 of these effects.
• 2: Target 1 monster you control; that monster is unaffected by other card effects until the End Phase.
• 4: Special Summon 1 "Alien" monster from your hand or GY.
• 6: Add 1 "Alien" card from your deck to your hand.
• 8: Banish 1 card on the field.
I feel it should be noted that although there are many spells and traps that support A-Counters, none of them are strictly "Alien" cards because they don't have the word "Alien" in their name. In fact, the only "Alien" card besides the archetype's monsters is Alien Brain, which has nothing to do with A-Counters but does still belong to the archetype. Whether you'd like to rephrase the 6-counter effect because of this or keep it as-is is your decision, but I thought you would like that bit of info in case you didn't already know.