Hi Uerm,
Lets call your data mycellarray. You can padd the second dimension of all tensors to have the same length as the one with the longest Y dimension as follows:
[~,b,~]=cellfun(@size,mycellarray) % get size of Y on each tensor
idx_padd=max(b)-b; % find difference from max Y dimension
for ii=1:length(mycellarray)
mycellarray{1,ii}= padarray(mycellarray{1,ii},[0 idx_padd(ii) 0],0,'post'); %padd
end
