I have to start by saying that I wouldn't personally add any altcoins to my portfolio at this time since I still believe Bitcoin is going to decline at least a little before the major bull run. Tomorrow at the latest we should see if Bitcoin breaks out of its short-term wedge. It's more likely to break down than up, but we'll just have to wait and see. I believe the altcoins I mention in this post would not only perform tremendously well if BTC were to keep climbing but also hold their price relatively well if Bitcoin falls closer to 7000.
EOS
It should be about time to start the fifth wave and make new highs. Holding nicely on the 50-day moving average. The question with EOS right now is, what will the reaction to the mainnet be like. Excitement or "buy the rumor, sell the news". I've marked the end of the fifth wave as an 1:1 extension of the third wave for now.
Ontology (ONT)
Chart has a lot of similarities to EOS, although the timeframe is much shorter. Ontology has held really strong during every Bitcoin correction, and it's again just waiting to rocket up again. Mainnet coming at the end of June.
Nuls
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Good-looking cup and handle. I can't explain why the price didn't take a bigger hit when the mainnet was delayed. Nuls looks extremely strong. Held its gains well while Bitcoin dropped in May.
Electra (ECA)
5-wave structure going up, correction, and bounce from the 0.5 Fibonacci level. If this textbook movement continues we should see another five waves up and some major gains with it. 22 sats seems like a strong support at this stage. Electra should have a positive month with many new updates coming, most notably atomic swaps.