Have an idea for TM's. Would like feedback.

This may be a little lengthy but if you have time please hear me out.
So, I've been thinking on the addition of TM's in the game and I think it would be a neat idea especially since one hugely discouraging aspect of the game is evolving unfavorable moves on a strong Pokemon you have put much effort in. I understand that it is also a factor to make you go out and get more Pokemon in order to get those better moves but getting unfavorable moves on a dragonite, snorlax, tyranitar etc. is a bit more frustrating and also harder to make up since they're already hard to come by.
Therefore, TM's would be a big help and also make the longevity of the game better since it would be fun messing with Pokemon moves and also collecting all the TM's. It could also make our favorite Pokemon more viable and also make other Pokemon that are strong and have good stats but have bad moves more usable in gyms on off. and def.
So here's the idea:
1. Have a screen with TM's listed and all as question marks. I'd say have the 50 TM's released in gen 1 be available to us for now.
2. To be unlocked you need TM tokens that drop from Pokestops, presumably at low rates, as low as maybe an evo item to prevent people from getting every TM in 1 week.(also if TM's were as rare as evo items I'd be extremely careful on what move to change as I've spun 250 stops for no items!) Also you need 1 token per move so if you unlock ice beam you still need a token to grab it and use again.
3. Using the TM token, you go to the screen and unlock a TM of your choice and, as in the other Pokemon games, it's a one time thing. So you get one token, unlock psychic and teach it to an exeggutor that has seed bomb or something like that.
4. A Pokemon can only have 1 TM used on it and this would be to prevent you from selecting the most optimal moves right before a gym battle and also to make you more wise and careful when teaching a mon a move since it is stuck with it permanently
5. You can change the quick move or charge move. One time like I said
6. A Pokemon can learn a move that it is in fact able to learn. This would be taken from the handheld games I'm sure. (Ex. Can't teach arcanine water gun or vaporeon wing attack but dragonite can learn ice beam etc.) or maybe niantic will have a list of possible moves a mon can learn from a TM however when it evolves it's moves are chosen like how they are now from a choice of 2 quick and 3 charge. This would be to limit absolute freedom on the move you can give a Pokemon. For example tyranitar already has its set 2 quick and 3 charge upon evo and let's say there are 5 TM's it can be taught that it can't learn from evo. I hope I said that in a clear way haha. Also you may choose a move to compensate for a weakness (etc. dragonite learning thunder to be able to hit lapras, but you'd lose out on stab so yeah we have to ponder what moves to give as in the other games)
Also the 1 TM per Pokemon is fair I think since sometimes we get unfavorable quick and charge moves. You'd only get to change one so you'd have to be smart on where it would help. Or if one is offensive and the other move is defensive then change the move to make it an attacker or defender etc.
So to recap: spin a pokestop, get lucky with a TM token, go unlock a TM, get earthquake, teach it to tyranitar that has fire blast as a charge move. Then that tyranitar can't be taught anything new.

I feel like this is good especially since some moves get nerfed, making our stronger Pokemon not as strong and our hard work, dust and time walking irrelevant, or a Pokemon getting nerfed, as in the lapras case.. Now it's bad to defend with but its still, in my opinion, a great attacker into dragonite and other weak to ice mons. But we have probably worked on our defensive lapras more and now to salvage them at least a little we can change one move to a more offensive type. Also machamp is stronger with new moves but perhaps we have an old machamp with good IV's and sub optimal moves.. This is an opportunity to make that machamp viable.

I'm not saying this idea out of frustration of my lapras getting nerfed( I still use it to attack) or the move changes or whatever.. I just think it would be healthy for the game since right now there is no compensation to niantic changing things in regards to Pokemon and moves.. They nerf moves and Pokemon and now we as a community are frustrated that mons we have spent hours and hours and dust on are not as strong and basically makes our effort worthless.. Why invest dust and walking a buddy if it will just get nerfed and become irrelevant? Niantic doesn't compensate that but at least the ability to change 1 move with luck from a pokestop can help us as players be smarter with our Pokemon and moves. This will also alleviate some of the frustration and risks when evolving and also when niantic changes moves and stuff.

Another thing I thought of literally while typing this is the fact that it would make gym battles way more exciting. I'm level 31 and have fought over 1000 gyms, so I'm sure I can speak for many other players when I say that I have memorized what moves Pokemon can know so when I am up against them I know what will hit me.. When against dragonite I know either hurricane, hyper beam or outrage will hit me.. But imagine using lapras against dragonite, which Has a normal, flying and dragon charge move.. But then all of a sudden getting hit with a thunder.. Your lapras won't be able to take on 2-3 dragonites anymore. Same with using a dragonite to kill a vaporeon.. We all know water moves won't be effective but imagine getting hit with an ice beam? Sure it loses stab but that ice beam will still hurt dragonite. Plus customizing our Pokemon to moves we like etc.. I just see many pros to TM's.
Let me know what you guys think. I think I got everything down. Let's have a discussion or not if this idea just flat out sucks haha. Also I'm Sorry it's so long!