Gaining

Well since Breads, rice, and pasta are allowed, It would be possible to gain on a Vegan diet.

Hi, I'm 100% vegetarian and 85% vegan.
In the last couple of years I gained almost 20 kg. And that wasn't difficult. The key is to always eat more than you think you could or should.

And a lot of vegan products are not so 'healthy' as you think. Nut bars, cookies with a lot of fat, chocolate, vegan meat,...

I think you can gain a lot as a vegan. In my case it went all to my belly.

A friend of my wife's went from about 170(ish) lbs to 268 in the first 4 years of going vegan.

From memory, it was a lot of bread, hummus, advocados, pastas with vegan sauces and any number of vegan deserts.

She was (haven't seen her since we moved back to Europe) a massive snacker and always ate vegan coconut macaroons with her coffee which she also took very sweet with hazelnut milk.

She also was a fan of this vegan dimsum place in Chinatown NYC. When we went I noted that they used a lot of different proteins from tofu to straight gluten and the seasonings contained white sugar along with aromatics and soy etc.

Another high calorie bar snack I recall her been keen on when she used to go to the local mexican was vegan cheese nachos which was tortilla chips, guacamole, refried beans , salsa and a coconut based melted cheese on top.

If you're looking for calorie rich vegan foods from Africa, look at using beans for making what in nigeria is called akara. They're a bean paste fried sort of pancake that you dip in a sort of corn porridge. Loads of calories for breakfast there.

A lot of the unhealthy gainer stuff is vegan too: transfats, white sugar, high fructose corn syrup so watch out where you're sourcing your calories from if you want to avoid these.