I don’t think so. You could ask in their thread, but as far as I can tell, the setup isn’t flexible.
Remembering stock sentences isn’t a bad thing, by the way. If you can really recall the sentence at will, then the grammar point will (by definition) be in there as well. In a sense, the sentence becomes your mnemonic for that particular grammar point.
I think being a beginner can be difficult because, as you say, it’s not so easy to practice speaking with other people or to read things with such limited vocab and grammar.
I’m by no means a grammar master, but I can share a few tips which have helped me.
About 10 years ago, I had gone through Genki 1 and Genki 2 before doing the Integrated Approach to Japanese, Intermediate, at university. I also passed JLPT 4 and 3 more than 10 years ago. At that time, reading and doing exercise from different books (Minna no Nihongo and Japanese for Busy People) helped me to get more exposure to the grammar and vocab I was studying. It also helped as grammar points would be explained in different ways. And JLPT practice tests are helpful. When you get questions wrong or feel that you really aren’t sure about a certain question you can go back and review those points.
Finally, I want to point out a problem in many language text books that I think a lot of people might not know about. It’s called interference. Many times, books and teachers like to present words and structures with similar meanings in the same lesson. There’s been research on this (see Paul Nation) which shows that this confuses the brain and it makes things harder to remember. When I was studying Khmer, I was very careful about not studying such language on the same day. Imagine, for example, that employer and employee where presented at the same time. It’s best to sure that you know one of them really well before learning the next one. Unfortunately, interference is a problem with wanikani too, and I don’t like learning a number of words meaning land/ground/earth too closely together.
Anyway, keep plugging a way and things will get easier once you have enough grammar for basic conversation or reading some easier text. Good luck!
I feel like past me wrote this post!
I felt exactly how you do only a month or so ago. I was great at remembering readings and individual words, but actually stringing things together using the grammar I learned was impossible. I think I’m on track to improving this, though. Here’s what I do…
Whenever I learn a new grammar point or “trick” through Genki or a friend, I then find multiple sentences and situations to use it in. Often I’ll just go through situations in my head and role play how the conversations would go.
After that, I try to create real sentences and post them to HelloTalk. You probably know, but HelloTalk is an app where you can post a message and others can read and correct it. It’s great for getting natural corrections. In my workflow, I think it is important to do this step quickly after the “role play”, because I don’t want to internalize something that is wrong.
I take the information I learn from the HelloTalk corrections and do the process again. Creating an imaginary situation, responding to myself (okay yeah, a lot of this is talking to myself), and then crafting sentences for HelloTalk.
So far it’s working for me. Instead of new grammar points just being textbook knowledge, I think I’m on track for internalizing proper use and appropriate situations.
I hope any bit of this will help you find what works best for you.
I would like to add that perhaps it wouldn’t be a bad idea to write down little texts, diary fragments if you like, using as much of the grammar you know. You don’t need anything for that except for a pen and paper, or a laptop screen ^^ What also works for me is just during the day, when I think of or want to say something that uses grammar and words I already learned in Japanese, I say it in Japanese too, just for myself, in my head. (And sometimes even out loud XP) That way you’re also using the language, even though there’s no (native) speaker to talk to.
Good luck on your journey ^^
I soooooooo feel you on this. In fact, I was just on my way to the forums to ask the very same question. The only difference is that I’m a bit further on in my Japanese studies (and probably have a worse memory than most). It’s good to hear that sample sentences help, but my problem is also the damn details…like when to use な, の and when to not use them. Writing examples for each and every form would be like writing a book after a while since there are sometimes small nuances with when some words are used. (Although, I think I get the tenses right about 95% of the time if I keep some simple exception in mind.) Maybe I just had better get started writing that book then…
PS. I think I have bald spots on the back of my head from hair pulling for not being able to remember all the necessary (and unnecessary) grammar.
I don’t think it’s impossible, although it may be difficult, and you’ll most likely need to use a dictionary with anything you try (also, you have been memorizing the Genki vocab, right?).
Here is a site that has free pdf files of simple graded readers AND audio files to go with some of them. At your level I’d advise starting with レベルA1 (The site is in Japanese, but just scroll down until you see the cover pictures):
http://jfkc.jp/clip/yomyom/index.html
Some people like Satori Reader (satorireader.com), and I’ve seen White Rabbit Graded Readers recommended frequently. Maybe someone who’s used those can comment more…
After you learn verb short forms in Genki lessons 8&9 you could try very simple children’s books. Perhaps your local library might have some to borrow? My library has a few shelved in the children’s non-fiction section with the foreign language learning books.
Others have mentioned writing down notes/diaries for yourself, talking to yourself, or using the Hellotalk app. There’s also italki.com, which has a free notebook function, where you can write in your target language (Japanese) and native speakers will correct your writing (similar to Hellotalk).
Hearing the patterns can also help. Do you consume any audio-visual Japanese media (tv/anime/music/youtube/podcasts)? If there’s something you enjoy, it can be fun to just listen; even if you don’t understand anyeverything, you may be able to pick out a grammar item that you’ve recently learned.
Oops, didn’t mean to write an encyclopedia! There are also tons more ideas in the Japanese resources thread: The Ultimate Additional Japanese Resources List!
Mango Languages takes it slow and might even seem (deceptively) too easy at first, but it does introduce some grammar concepts – verb tenses, te-form, particles. Each lesson is about 15 minutes and can be put on autoplay. If you’re in the US and have a public library card, you can probably get it for free. It doesn’t go into in-depth explanations of the concepts, but since you’ve already been doing Genki it will probably just help you digest what you’ve learned.
I’m also working through Genki 1 and I agree that finding reading material at beginner level is almost impossible. Satori Reader can allow you to read some NHK Web Easy articles but you will have to click on every annotation and you will probably not retain a lot. Also when reading you might know the vocab but not recognize the grammar structure because you haven’t learned it yet. I ordered some Graded Readers but shipping takes ages so I can’t comment on those.
My recommendation is:
I haven’t tried taking iTalki lessons yet but you can certainly do that at any level. Book a professional teacher and they should know how to deal with beginners. It should be useful even if you can’t express that much yet.
I’ve been playing around with Anki and trying to find ways for it to help me remember vocabulary and saw this post:
https://community.wanikani.com/t/ankiwanikani-20/9751
Maybe it can help you with typing out sentences or remembering grammar if you make the cards yourself and work on it repetitively by typing down answers similar to WaniKani. Then continue adding more complex sentences as you become more familiar with the grammar.
Question 1.) Are you doing everything in Genki?
Question 2.) No seriously are you?
Question 3.) The workbook exercises?
Question 4.) The reading comprehension exercises?
Question 5.) The open ended questions?
I have Genki and a bunch of textbooks, but I really like learning on the computer with drills that motivate me and keep me exposed to the new concepts with SRS methods.
So what works for me is NihongoMaster.com. (I don’t work for them, but I did add an affiliate link, I’m a fan.) The first Introductory Lessons free, where they teach you hiragana and katakana and very basic vocab/grammar. They have Beginner/Intermediate/Advanced where they are still adding lessons and up to N3 now. I’m still halfway through beginner where I get a short grammar lesson, usually with vocabulary and some kanji interspersed.
Here’s a snippet of an Advanced lesson where you’re reading manga and then you can listen in as well.
But I get great practice reading Japanese, listening to it, seeing how the kanji is written. I can add any kanji or vocab to my drills (been adding WK stuff). They have audio, so these words and sentences are ingrained in my head from listening to them over and over by different voice actors.
I get quizzed on my comprehension of lessons. Each lesson gives about 20-40 drills. If you need more practice you can increase the SRS mastery level, so you see it more than five times (or less if you want). I can really tell what I need practice on when I see something weeks later.
It’s not free, but at least you can try it out to start and see if you like the format.
I am yes, but other than the workbook, I don’t really have any way to be sure that I’m answering correctly. Is there a resource that has some sort of answer key for the Genki exercises?
There is in fact an answer key, yes. If you Google it you should be able to find it.
For questions without a true answer it gives a suggested answer.
Fantastic, I’ll check it out. Thanks!
Seconding this and adding that finding someone who will read it over and make corrections/give feedback would be great too to make sure you’re using it right. I’m sure someone here on WK could help out with that if you asked. 
This is similar to the method I use with grammar self study. I like to pick out some choice sentences that use a specific grammar point and I write them in my Japanese journal/study notebook, saying them out loud as I go. Then I repeat them like 900 times until they sound almost natural; this has done WONDERS for my speaking ability–reading aloud in Japanese to myself is something I do whenever I can. I’ve also found that it makes formulating your own, organic verbal responses much quicker, too. I will occasionally record myself as well, just to hear where I’m struggling the most (awkward 
) . I love the idea of putting things on HelloTalk for the corrections though, so I’ll have to try that!
Also, I often imagine I’m having a phone conversation in Japanese (with myself, yep) and respond to my thoughts out loud; I do this a lot in my car, since I have a terribly long commute–it has been effective and passes the time, too ^___^
I’ve tried various language exchange websites such my MLE, iTalki, and plenty of others. Always with the same results. I just simply don’t have enough knowledge for it yet, which is a shame 
I expected the oppotise, in fact, seeing as the convos would be mostly be in English so they’d get a lot of practice in! ^^
I guess I’ll stick to discussion boards for now.
Most Japanese on those sites are terrible at English and just want to speak to a foreigner (in my experience), the same as you were expecting to speak English with some Japanese mixed in.
This is a big generalisation, and some are pretty competent , but its a skill, so its a pyramid, unskilled at the bottom and skilled at the top.
This is the method I am currently using only with HiNative, but usually what happens is, they’ll start suggesting to express my senteces with completely different grammar constructions (which most of the time I don’t know) and then I am totally confused and discouraged…
Everyone already gave some really good advice so I’ll just add a little bit on top: write your own sentences. Anytime I learn a new grammar point, I take a few minutes to write my own sentences using that grammar point, and I keep a “diary” of them in a notepad on my phone. They don’t have to be these really articulate/advanced sentences, just something that YOU composed yourself. I think the more you do that, and if you do that as soon as you’re learning a grammar point, that it will start to stick with you better. I’m still fairly new too, but that’s seemed to work best with me.