Simply don't train it at all. Training a Pokemon is what causes it to level up.
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They stop Lv. up at 100. You can see that your pokemon's EXP bar doesn't increase at Lv. 100.
no Pokemon can learn rock smash by leveling up you have to get the hm.
The only pokemon to get fly by leveling up are Salamance and Rayquaza.
bannete or clefable
Sing is not a TM (Technical Machine). It is a move that only certain Pokemon learn. You can only learn it by leveling up certain Pokemon (Skitty, for example, learns Sing by leveling up).