Champ for trash player
so a friend of mine is extremely trash, to a point where he feeds with garen and miss fortune every game(including some beginner bot games and 100% intermediate bot games). He asked me to recommend a champion that can damage and sustain/lifesteal at the same time after he saw me use a fed tryndamere
. he has tried udyr but hasn't been much good at him.
please recommend a easy champion where timing is less essential and all skills are easy to use.
any role is fine as long as it meats the requirements above.

Both have sustain, are tanky and are rather easy to play. Although i'd suggest Vlad since it would be a waste to invest effort into Swain since he is getting reworked soon.
i almost forgot him. He's even tankier and all you've got to do is hit cleavers.
and the Boys... Super easy to play, high impact if you ult the correct target. All you need to focus on is positioning because your E and minions will CS for you!
Or if you prefer to be tanky just play
extremely easy to play, once you get 6 you can duel most people in the game (minus like fiora) all you need to focus on him is positioning and stackin Q