What TV show is about a teenager who finds a robot and can merge with the robot and transform into different things and fight elementals?

Question

In the TV show the kid finds a robot and fights elementals. The elementals can merge and get more crystals on their head. The kid has friends and together they fight the evil people that are making new elementals and making them stronger. The main character can transform into different forms; like a heavy tank form, speed form etc. The robot has emotions and it also has feelings of pain.

Answer 1

As per Ifurini's comment, this could be the 2013 version of Max Steel, asked after here.

Maxwell "Max" McGrath/Max Steel (voiced by Andrew Francis): A turbo-powered boy, Max is taken to the secret "N-Tek" facility, and discovers that his uncle, Forge Ferrus, is the commander and co-Founder of N-Tek, along with Jim McGrath and Miles Dredd. Max later meets Steel, an Ultralink that will change Max's life and will later turn Max into the world's greatest and most powerful superhero in the world known as Max Steel. Maxwell and Steel don't know a lot about their past and also they don't know about N-Tek, especially N-Tek's true mission that Forge Ferrus is hiding from Max and Steel. Max has a friend named Kirby and has a crush on a girl named Sydney. Max wears a camouflage mode, so no one can see him with the Turbo Base Mode on (which can't be removed because it's permanently on Max) and he doesn't wants anyone to know that he is Max Steel. He is able to generate Tachyon Unlimited Radiant Bio-Optimized (TURBO) energy, and control it with the help of Steel, thereby creating the persona of Max Steel. As Max Steel, Max has superpowers (superhuman strength, speed, durability, and agility) and a cadre of TURBO Modes for different combat scenarios including; Base, Strength, Camo (Max's civilian mode), Flight, Scuba, Super, Speed, Stealth, Cannon, Clone, Mimic (Steel's turbo mode), Heat, Rocket, Spike, Nova, Titan, Cannon Spike, Hydro Heat, Sonic Flight, Exo Strength, Hammer Claw, Prime, Hunter and Mega. Following the events of Turbo-Charged, Max obtains new, completely technological modes, being those: Armor, Jet Pack, Wave Rider, Sniper, Rocket Spear and Mountain Combat.

....

The Elementors (Fire and Air, voiced by Andrew Francis; Earth and Water, voiced by Brian Drummond; Metal voiced by Trevor Devall): The Elementors are Ultralinks that each manifested a body from the elements and are able to combine themselves into multi-elemental creatures. Originally, there were a group of four Elementors based around the four elements that were sent to Earth to aid Dredd for their own agenda. The first three, Fire Elementor, Earth Elementor, and Water Elementor, were eventually captured by N-Tek. But during an attempted rescue by Air Elementor in Elements of Surprise, due to an accident with an inhibitor mounted on his head, the four Elementors' bodies ended up being fused into the 4-cored Ultimate Elementor that uses all their powers and combine them to produce ice and lightning. Though the four personalities conflicted at first, they eventually put aside their squabbles for their mutual hatred towards Max Steel. In season two, a Megalink Elementor named Metal Elementor is introduced in Full Metal Racket. In Ultralink Hunter, Metal Elementor sets Ultimate Elementor up by giving him 24 hours to catch Max Steel. After Ultimate Elementor is defeated after managing to catch Steel and Ven-Ghan, Metal Elementor reveals his ruse and absorbs Ultimate Elementor to become the 5-cored Mega Elementor.

It's not crystals, but the cores could be what you're thinking of.

Trailer

Footage of Elementors with glowing red cores in their heads